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Stöger-Pollach M, Ederer M. Experimental evidence of magnetism in a 2D electron gas at the CoO/Co 3O 4 interface by employing EMCD. Micron 2024; 185:103687. [PMID: 39053049 DOI: 10.1016/j.micron.2024.103687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 06/25/2024] [Accepted: 06/26/2024] [Indexed: 07/27/2024]
Abstract
In the present study we investigate the CoO/Co3O4 interface in order to determine its intriguing magnetic behavior, which can be utilized for tailoring magnetic properties, enabling spin transport, enhancing magnetic coupling, tuning device functionalities, and realizing miniaturized magnetic devices for various technological applications. We decipher the magnetic properties of the CoO/Co3O4 interface from first principles calculations using Wien2k and probe them experimentally by employing electron energy-loss magnetic chiral dichroism (EMCD), which is an electron-energy loss spectrometry (EELS) based technique in the transmission electron microscope (TEM). Both, theory and experiment, are in perfect agreement and result in a ferromagnetic 2D-electron gas of 5Å thickness directly at the interface.
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Affiliation(s)
- Michael Stöger-Pollach
- University Service Center for Transmission Electron Microscopy (USTEM), Technische Universität Wien, Wiedner Hauptstraße 8-10, Wien 1040, Austria; Institute of Solid State Physics, Technische Universität Wien, Wiedner Hauptstraße 8-10, Wien 1040, Austria.
| | - Manuel Ederer
- University Service Center for Transmission Electron Microscopy (USTEM), Technische Universität Wien, Wiedner Hauptstraße 8-10, Wien 1040, Austria; Institute of Solid State Physics, Technische Universität Wien, Wiedner Hauptstraße 8-10, Wien 1040, Austria
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2
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Bouteiller H, Fontaine B, Perez O, Hébert S, Bourgès C, Matsushita Y, Mori T, Gascoin F, Halet JF, Berthebaud D. Enhancement of Thermoelectric Performance through Transport Properties Decorrelation in the Quaternary Pseudo-Hollandite Chalcogenide Rb 0.2Ba 0.4Cr 5Se 8. Inorg Chem 2024; 63:16655-16666. [PMID: 39189684 DOI: 10.1021/acs.inorgchem.4c01867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
The novel quaternary compound Rb0.2Ba0.4Cr5Se8 was synthesized and characterized in both single crystal and polycrystalline forms. Crystallizing in the monoclinic crystal system (space group C2/m, cell parameters a = 18.7071(4) Å, b = 3.6030(1) Å, c = 8.9637(3) Å, β = 104.494(2)°) and isostructural to pseudo-hollandite compounds, it features mixed Rb and Ba occupancy within its one-dimensional channels. High-temperature X-ray diffraction revealed no decomposition up to 973 K, and the thermal expansion coefficient at 300 K was determined to be 2.6(1)·10-5 K-1. Spin-polarized density functional theory (DFT) calculations showed that the density of states for Rb0.2Ba0.4Cr5Se8 is more polarized than that of Ba0.5Cr5Se8, resulting in a higher Seebeck coefficient, which was experimentally confirmed to reach a peak value of 400 μV·K-1 at 620 K. Resistivity measurements indicated a degenerate semiconducting behavior below 550 K, with a resistivity peak of 100 mΩ·cm at that temperature, leading to a maximum power factor of 0.21 mW·m-1·K-2. Thermal conductivity measurements indicated low values around 0.8 W·m-1·K-1 in the 300-900 K range, resulting in a thermoelectric figure of merit of 0.22 at 873 K. Decorrelated transport properties observed in this double-inserted pseudo-hollandite compound make Rb0.2Ba0.4Cr5Se8 a good example of beneficial synergistic effects for higher thermoelectric performance.
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Affiliation(s)
- Hugo Bouteiller
- Laboratoire CRISMAT, ENSICAEN, UNICAEN, CNRS, Normandie Univ. (UMR 6508), Caen F-14000, France
- CNRS-Saint-Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
| | - Bruno Fontaine
- Univ Rennes, CNRS, Ecole Nationale Supérieure de Chimie de Rennes (ENSCR), Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226, Rennes F-35000, France
- Saint-Cyr Coëtquidan Military Academy, CReC, Guer F-56380, France
| | - Olivier Perez
- Laboratoire CRISMAT, ENSICAEN, UNICAEN, CNRS, Normandie Univ. (UMR 6508), Caen F-14000, France
| | - Sylvie Hébert
- Laboratoire CRISMAT, ENSICAEN, UNICAEN, CNRS, Normandie Univ. (UMR 6508), Caen F-14000, France
| | - Cédric Bourgès
- International Center for Young Scientists (ICYS), National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
- International Center for Young Scientists (ICYS), National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Yoshitaka Matsushita
- National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Takao Mori
- Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Japan
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8671, Japan
| | - Franck Gascoin
- Laboratoire CRISMAT, ENSICAEN, UNICAEN, CNRS, Normandie Univ. (UMR 6508), Caen F-14000, France
| | - Jean-François Halet
- CNRS-Saint-Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
- Univ Rennes, CNRS, Ecole Nationale Supérieure de Chimie de Rennes (ENSCR), Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226, Rennes F-35000, France
| | - David Berthebaud
- CNRS-Saint-Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
- Nantes Université, CNRS, Institut des Matériaux de Nantes Jean Rouxel, IMN, Nantes F-44000, France
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Nitika, Arora S, Ahlawat DS. High-throughput screening on optoelectronic properties of two-dimensional InN/GaN heterostructure from first principles. J Mol Model 2024; 30:318. [PMID: 39215826 DOI: 10.1007/s00894-024-06121-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024]
Abstract
CONTEXT A novel 2D InN/GaN lateral heterostructure (LHT) was simulated by stitching monolayer of 2D InN and monolayer of 2D GaN. The structural stability, electronic structure, and optical properties were systematically investigated using first-principle calculations and by considering the effects of strain. The results indicated that the designed heterostructure has a direct bandgap of 2.26 eV which is further affected by applied biaxial strain. The bandgap of 2D InN/GaN lateral heterostructure decreases with the increase in biaxial strain, and tensile strain triggers a direct-to-indirect energy gap changeover at + 6%. Additionally, under compressive strain, heterostructure remains a direct bandgap semiconductor. Furthermore, the strain significantly affects the optical characteristics of lateral heterostructure. It has been noticed that the first optical absorption peak moves from 2.51 eV (ɛ = - 4%) to 1.40 eV (ɛ = 10%). Therefore, 2D InN/GaN lateral heterostructure provides an approachable way for utilizing in optoelectronic devices through the creation of in-plane lateral heterostructures. METHODS We performed all the computations using a self-consistent method based upon density functional theory. We used the PBEsol functional in the GGA to account for the exchange-correlation effects. We introduced a 10-Å vacuum region in the z-direction to avoid interaction between periodic images. We considered non-negligible weak dispersion correction in the lateral heterostructure using Grimme's DFT-D3 approach. In this study, we also computed the electrical and optical properties employing the local modified Becke-Johnson (lmBJ) exchange potential under meta-GGA functional to obtain more precise results.
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Affiliation(s)
- Nitika
- Department of Physics, Chaudhary Devi Lal University, Sirsa-125055, Hry, Sirsa, India
| | - Sandeep Arora
- Department of Physics, Chaudhary Devi Lal University, Sirsa-125055, Hry, Sirsa, India
- Govt. Model Skt. Sen. Sec. School, Rania-125076, Sirsa, India
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Vero K, Borah JP. Transformation of in-plane to out-of-plane anisotropy in MnBi alloy for permanent magnet application: a First-principles study. Sci Rep 2024; 14:19015. [PMID: 39152191 PMCID: PMC11329647 DOI: 10.1038/s41598-024-69908-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/09/2024] [Indexed: 08/19/2024] Open
Abstract
The low-temperature phase (LTP) MnBi exhibits remarkable ferromagnetic properties at room temperature. However, below its Curie temperature ( T C ), a phase transition occurs around 613 K due to diffusion of Mn into interstitial sites, raising concerns about its structural and magnetic properties. Furthermore, the presence of in-plane anisotropy in LTP-MnBi alloy at low temperatures raises concerns about its suitability for use in permanent magnet applications, even at higher temperature. Therefore, this study examines the structural and magnetic properties of pure LTP-MnBi and its successive Ni-doped and Fe-substituted alloys using first-principles study based on density functional theory (DFT). To prevent Mn diffusion into interstitial sites, Ni doping is employed. Additionally, the incorporation of Ni successfully addresses the in-plane anisotropy issue in LTP-MnBi, transforming it into out-of-plane anisotropy. Moreover, we explored the potential advantages of substituting Fe for one of Mn site. This substitution aims to improve the observed dynamical instability in Ni-doped alloy and to further enhanced the magnetocrystalline anisotropy energy (MAE) of the material, resulting in an MAE of 3.21 MJ/m3, along with a T C of 523 K. Therefore, the coexistence of high MAE and moderate T C in the Mn0.5Fe0.5Bi-Ni alloy presents viable option for its application in permanent magnet technology.
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Affiliation(s)
- Khoveto Vero
- Department of Physics, National Institute of Technology Nagaland, Chűmoukedima, Nagaland, 797103, India
| | - J P Borah
- Department of Physics, National Institute of Technology Nagaland, Chűmoukedima, Nagaland, 797103, India.
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Nitika, Arora S, Ahlawat DS. Mechanical strain effect on the optoelectronic properties and photocatalysis applications of layered AlN/GaN nanoheterostructure. J Mol Model 2024; 30:309. [PMID: 39138708 DOI: 10.1007/s00894-024-06103-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 08/05/2024] [Indexed: 08/15/2024]
Abstract
CONTEXT The aim of this work is to use first principles calculations to examine the effects of different mechanical strains on the optoelectronic and photocatalytic capabilities of the 2D/2D nanoheterostructure of AlN/GaN. By utilizing the lmBJ (Meta-GGA) and PBEsol (GGA) functional, the bandgap of the nanoheterostructure is calculated and found to be 4.89 eV and 3.24 eV. Simulated 2D AlN/GaN nanoheterostructure exhibits exceptional optical and electronic characteristics under applied biaxial tensile and compressive strains. The band gap changes from 4.89 to 3.77 eV, while the energy gap nature transitions from direct to indirect during tensile strain fluctuations of 0% to 8%. Strain is also found to have a significant effect on the optical absorption peaks. And a 0-8% rise in tensile strain causes the initial absorption peak of the 2D AlN/GaN nanoheterostructure to shift from 4.88 to 4.20 eV, which results in a 14% red shift in photon energy for every 2% change in strain. Furthermore, the optimum bandgap and band edge positions of the 2D AlN/GaN nanoheterostructure enable the water redox process to produce hydrogen and oxygen for wide range of pH. Thus, modification via strain may be an effective method for altering the optical as well as electronic characteristics of a 2D AlN/GaN nanoheterostructure, and this study may pave the way for new applications of this material in optoelectronic devices in the future. METHODS In the current work, density functional theory is used to explore every attribute of the 2D AlN/GaN nanoheterostructure. To characterize the electronic exchange-correlation, we used the PBEsol functional. In order to prevent any interlayer contact between periodicity of images, a vacuum is produced along the z-direction of approximately 10 Å. To increase the precision of bandgap prediction, the electronic and optical characteristics were computed using the meta-GGA lmBJ functional. To account for interlayer van der Waals interactions, nanoheterostructure computations were performed using the DFT-D3 functional.
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Affiliation(s)
- Nitika
- Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055, (Hry.), India
| | - Sandeep Arora
- Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055, (Hry.), India
- Govt. Model Skt. Sen. Sec. School, Rania, 125076, Sirsa, India
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Ahmed Ahmed WA, Özdemir EG, Aliabad HAR. Structural, wide band gap half-metallic, and pressure-dependent thermodynamic predictions of Li 2TMMgO 6 (TM = V, Nb, and Ta) double perovskites. J Mol Model 2024; 30:305. [PMID: 39134902 DOI: 10.1007/s00894-024-06107-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Accepted: 08/07/2024] [Indexed: 09/11/2024]
Abstract
CONTEXT Li2VMgO6, Li2NbMgO6, and Li2TaMgO6 double perovskite compounds were energetically the most stable in the FM phase. The lattice constants were 7.63 Å, 7.94 Å, and 7.95 Å, and the Curie temperatures were 910.451 K, 930.739 K, and 1258.821 K, respectively. The wide bandgap semiconductor characters were provided in the GGA-PBE methods as 2.139 eV, 4.209 eV, and 5.007 eV, respectively. This wide band gap semiconductor state in the majority carriers and the metallic state in the minority states made these double perovskites true half-metallic ferromagnetics. The bulk modulus obtained in the ground state calculations and the values obtained from thermodynamic calculations were relatively close. Debye temperatures in the initial state conditions were 747 K, 685.13 K, and 587.77 K, respectively. The total magnetic moment values were calculated as 3.00 µB/f.u. The most significant contribution to this value came from oxygen atoms. METHODS The theoretical calculations of Li2VMgO6, Li2NbMgO6, and Li2TaMgO6 double perovskite alloys were performed using the WIEN2k program developed by Blaha et al. The electronic calculations were made with GGA-PBE, GGA + mBJ, and GGA + U approximations in the space number 225 and the Fm-3 m symmetry group. The thermodynamic calculations were performed using Gibbs2. In thermodynamic calculations, temperature increases were determined as 100 K and temperature values were increased from 0 to 1200 K.
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Affiliation(s)
- Wisam Ayad Ahmed Ahmed
- Department of Physics, Faculty of Science, Gazi University, 06560, Teknikokullar, Ankara, Türkiye
- Department of Physics, Graduate School of Natural and Applied Sciences, Gazi University, Teknikokullar, 06560, Ankara, Türkiye
| | - Evren Görkem Özdemir
- Department of Physics, Faculty of Science, Gazi University, 06560, Teknikokullar, Ankara, Türkiye.
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Dai Y, Terskikh V, Wu G. A combined solid-state 1H, 13C, 17O NMR and periodic DFT study of hyperfine coupling tensors in paramagnetic copper(II) compounds. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2024; 132:101945. [PMID: 38968703 DOI: 10.1016/j.ssnmr.2024.101945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 06/21/2024] [Accepted: 06/24/2024] [Indexed: 07/07/2024]
Abstract
We report solid-state 1H, 13C, and 17O NMR determination of hyperfine coupling tensors (A-tensors) in several paramagnetic Cu(II) (d9, S = 1/2) complexes: trans-Cu(DL-Ala)2·H217O, Cu([1-13C]acetate)2·H2O, Cu([2-13C]acetate)2·H2O, and Cu(acetate)2·H217O. Using these new experimental results and some A-tensor data available in the literature for trans-Cu(L-Ala)2 and K2CuCl4·2H2O, we were able to examine the accuracy of A-tensor computation from a periodic DFT method implemented in the BAND program. We evaluated A-tensors on 1H (I = 1/2), 13C (I = 1/2), 14N (I = 1), 17O (I = 5/2), 39K (I = 3/2), 35Cl (I = 3/2), and 63Cu (I = 3/2) nuclei over a range spanning more than 3 orders of magnitude. We found that the BAND code can reproduce reasonably well the experimental results for both A-tensors and nuclear quadrupole coupling tensors.
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Affiliation(s)
- Yizhe Dai
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, K7L 3N6, Canada
| | - Victor Terskikh
- Metrology, National Research Council Canada, Ottawa, K1A 0R6, Canada
| | - Gang Wu
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, K7L 3N6, Canada.
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Mahatha SK, Phillips J, Corral-Sertal J, Subires D, Korshunov A, Kar A, Buck J, Diekmann F, Garbarino G, Ivanov YP, Chuvilin A, Mondal D, Vobornik I, Bosak A, Rossnagel K, Pardo V, Fumega AO, Blanco-Canosa S. Self-Stacked 1T-1H Layers in 6R-NbSeTe and the Emergence of Charge and Magnetic Correlations Due to Ligand Disorder. ACS NANO 2024. [PMID: 39086092 DOI: 10.1021/acsnano.4c02005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
The emergence of correlated phenomena arising from the combination of 1T and 1H van der Waals layers is the focus of intense research. Here, we synthesize a self-stacked 6R phase in NbSeTe, showing perfect alternating 1T and 1H layers that grow coherently along the c-direction, as revealed by scanning transmission electron microscopy. Angle-resolved photoemission spectroscopy shows a mixed contribution of the trigonal and octahedral Nb bands to the Fermi level. Diffuse scattering reveals temperature-independent short-range charge fluctuations with propagation vector qCO = (0.25 0), derived from the condensation of a longitudinal mode in the 1T layer, while the long-range charge density wave is quenched by ligand disorder. Magnetization measurements suggest the presence of an inhomogeneous, short-range magnetic order, further supported by the absence of a clear phase transition in the specific heat. These experimental analyses in combination with ab initio calculations indicate that the ground state of 6R-NbSeTe is described by a statistical distribution of short-range charge-modulated and spin-correlated regions driven by ligand disorder. Our results demonstrate how natural 1T-1H self-stacked bulk heterostructures can be used to engineer emergent phases of matter.
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Affiliation(s)
- Sanjoy K Mahatha
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001, India
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Jan Phillips
- Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela, Spain
- Instituto de Materiais iMATUS, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela, Spain
| | - Javier Corral-Sertal
- Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela, Spain
- CiQUS, Centro Singular de Investigacion en Quimica Biolóxica e Materiais Moleculares, Departamento de Quimica-Fisica, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - David Subires
- Donostia International Physics Center (DIPC), E-20018 San Sebastián, Spain
- University of the Basque Country (UPV/EHU), Basque Country, Bilbao 48080 Spain
| | - Artem Korshunov
- European Synchrotron Radiation Facility (ESRF), BP 220, F-38043 Grenoble Cedex, France
| | - Arunava Kar
- Donostia International Physics Center (DIPC), E-20018 San Sebastián, Spain
| | - Jens Buck
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
| | - Florian Diekmann
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
| | - Gaston Garbarino
- European Synchrotron Radiation Facility (ESRF), BP 220, F-38043 Grenoble Cedex 9, France
| | - Yurii P Ivanov
- Electron Spectroscopy and Nanoscopy, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Andrey Chuvilin
- CIC Nanogune, E-20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Debashis Mondal
- Consiglio Nazionale delle Ricerche (CNR)- Istituto Officina dei Materiali (IOM), Laboratorio TASC in Area Science, 34149 Trieste, Italy
- Sovarani Memorial College, Jagatballavpur, Howrah 711408, India
| | - Ivana Vobornik
- Consiglio Nazionale delle Ricerche (CNR)- Istituto Officina dei Materiali (IOM), Laboratorio TASC in Area Science, 34149 Trieste, Italy
| | - Alexei Bosak
- European Synchrotron Radiation Facility (ESRF), BP 220, F-38043 Grenoble Cedex, France
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Victor Pardo
- Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela, Spain
- Instituto de Materiais iMATUS, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782 Santiago de Compostela, Spain
| | - Adolfo O Fumega
- Department of Applied Physics, Aalto University, 02150 Espoo, Finland
| | - Santiago Blanco-Canosa
- Donostia International Physics Center (DIPC), E-20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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Javed M, Akbar N, Khan AA, Masood A, Ahmed N, Khan MJ, Ahmed N, Khisro SN, Hameed MASA. Tailoring structural and optical properties of Cu(II)-induced MgAl 2O 4 nanoparticles and their response to toxic dyes under solar illumination. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:53532-53551. [PMID: 39192152 DOI: 10.1007/s11356-024-34753-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 08/15/2024] [Indexed: 08/29/2024]
Abstract
Worldwide environmental challenges pose critical problems with the growth of the global economy. Addressing these issues requires the development of an eco-friendly and sustainable catalyst for degrading organic dye pollutants. In this study, copper-doped magnesium aluminates (CuxMg1-xAl2O4) with x = 0.0-0.8 were synthesized using a citrate-based combustion route. The inclusion of Cu(II) significantly impacted the structural, microstructural, optical, and photocatalytic activity of the catalyst. Rietveld analysis of X-ray diffraction powder profiles revealed single-phase spinels crystallized in the face-centered cubic unit cell with Fd 3 ¯ m space group. Chemical states of the ions, surface morphology, and elemental investigation were analyzed by X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy, respectively. UV-visible and diffuse reflectance spectroscopies confirmed the reduction of the band gap due to Cu(II) doping, validated by first-principle investigations using the WIEN2k code. The catalyst with x = 0.8 showed higher photocatalytic efficacy (90% and 93%) for removing two azo organic dye pollutants, rhodamine B and methyl orange, respectively, within 120 min. Degradation kinetics followed a pseudo-first-order mechanism. The doped (0.8) sample was structurally and morphologically stable and reusable under visible irradiation, retaining performance after three runs. Scavenger studies confirmed hydroxyl and superoxide radicals' involvement in the degradation. This work presents an effective approach to enhancing CuxMg1-xAl2O4 catalysts' photodegradation performance, with potential applications in pharmaceuticals and wastewater remediation.
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Affiliation(s)
- Muhammad Javed
- Department of Physics, University of Kotli Azad Jammu and Kashmir, Kotli, 11100, Pakistan
| | - Naeem Akbar
- Department of Physics, University of Kotli Azad Jammu and Kashmir, Kotli, 11100, Pakistan
| | - Ayaz Arif Khan
- Department of Physics, University of Azad Jammu and Kashmir, Muzaffarabad, 13100, Pakistan
| | - Asad Masood
- Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
| | - Naeem Ahmed
- Molecular Electrochemistry Laboratory, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Muhammad Junaid Khan
- Department of Physics and Applied Mathematics (DPAM), Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Nisar Ahmed
- Department of Physics and Applied Mathematics (DPAM), Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Said Nasir Khisro
- Department of Physics, University of Kotli Azad Jammu and Kashmir, Kotli, 11100, Pakistan
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Lévêque J, Rebolini E, Saúl A, Lepetit MB. Magnetic structure of a multiferroic compound: Cu 2OCl 2. Faraday Discuss 2024. [PMID: 39072418 DOI: 10.1039/d4fd00042k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The Cu2OCl2 compound has been shown to be a high-temperature spin-driven multiferroic system, with a linear magneto-electric coupling. In this paper we propose a complete study of its magnetic structure. We derive the low energy magnetic Hamiltonian using ab initio multi-reference configuration interaction and the spin structure using Monte-Carlo simulations. Among the three magnetic structures proposed in the literature from different experimental results, our calculations support the incommensurate cycloid magnetic structure with a q⃑ = (qa,0,0) propagation vector. Using symmetry analysis, we show that all experimental results (polarization, magnetic order, magneto-electric coupling) can be accounted for in the Fd'd'2 magnetic space group (2-fold axis along c⃑).
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Affiliation(s)
- Julien Lévêque
- CINAM, CNRS - Université d'Aix Marseille, Campus de Luminy - Case 913, Marseille, France.
- Institut Néel, CNRS, 25 Av. des Martyrs, Grenoble, France.
| | - Elisa Rebolini
- Institut Laue Langevin, 71 Avenue des Martyrs, CS 20156, Grenoble, France
| | - Andrés Saúl
- CINAM, CNRS - Université d'Aix Marseille, Campus de Luminy - Case 913, Marseille, France.
| | - Marie-Bernadette Lepetit
- Institut Néel, CNRS, 25 Av. des Martyrs, Grenoble, France.
- Institut Laue Langevin, 71 Avenue des Martyrs, CS 20156, Grenoble, France
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11
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Stishenko P, McSloy A, Onat B, Hourahine B, Maurer RJ, Kermode JR, Logsdail A. Integrated workflows and interfaces for data-driven semi-empirical electronic structure calculations. J Chem Phys 2024; 161:012502. [PMID: 38958157 DOI: 10.1063/5.0209742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 06/07/2024] [Indexed: 07/04/2024] Open
Abstract
Modern software engineering of electronic structure codes has seen a paradigm shift from monolithic workflows toward object-based modularity. Software objectivity allows for greater flexibility in the application of electronic structure calculations, with particular benefits when integrated with approaches for data-driven analysis. Here, we discuss different approaches to create deep modular interfaces that connect big-data workflows and electronic structure codes and explore the diversity of use cases that they can enable. We present two such interface approaches for the semi-empirical electronic structure package, DFTB+. In one case, DFTB+ is applied as a library and provides data to an external workflow; in another, DFTB+receives data via external bindings and processes the information subsequently within an internal workflow. We provide a general framework to enable data exchange workflows for embedding new machine-learning-based Hamiltonians within DFTB+ or enabling deep integration of DFTB+ in multiscale embedding workflows. These modular interfaces demonstrate opportunities in emergent software and workflows to accelerate scientific discovery by harnessing existing software capabilities.
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Affiliation(s)
- Pavel Stishenko
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, United Kingdom
| | - Adam McSloy
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Berk Onat
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Ben Hourahine
- SUPA, Department of Physics, John Anderson Building, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG, United Kingdom
| | - Reinhard J Maurer
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom and Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - James R Kermode
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Andrew Logsdail
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, United Kingdom
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12
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Wenzel M, Uykur E, Tsirlin AA, Pal S, Roy RM, Yi C, Shekhar C, Felser C, Pronin AV, Dressel M. Intriguing Low-Temperature Phase in the Antiferromagnetic Kagome Metal FeGe. PHYSICAL REVIEW LETTERS 2024; 132:266505. [PMID: 38996298 DOI: 10.1103/physrevlett.132.266505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 05/24/2024] [Indexed: 07/14/2024]
Abstract
The properties of kagome metals are governed by the interdependence of band topology and electronic correlations resulting in remarkably rich phase diagrams. Here, we study the temperature evolution of the bulk electronic structure of the antiferromagnetic kagome metal FeGe using infrared spectroscopy. We uncover drastic changes in the low-energy interband absorption at the 100 K structural phase transition that has been linked to a charge-density-wave (CDW) instability. We explain this effect by the minuscule Fe displacement in the kagome plane, which results in parallel bands in the vicinity of the Fermi level. In contrast to conventional CDW materials, however, the spectral weight shifts to low energies, ruling out the opening of a CDW gap in FeGe.
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13
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Krpenský J, Horák M, Kabát J, Planer J, Kepič P, Křápek V, Konečná A. Analytical electron microscopy analysis of insulating and metallic phases in nanostructured vanadium dioxide. NANOSCALE ADVANCES 2024; 6:3338-3346. [PMID: 38933858 PMCID: PMC11197434 DOI: 10.1039/d4na00338a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 05/02/2024] [Indexed: 06/28/2024]
Abstract
Vanadium dioxide (VO2) is a strongly correlated material that exhibits the insulator-to-metal transition (IMT) near room temperature, which makes it a promising candidate for applications in nanophotonics or optoelectronics. However, creating VO2 nanostructures with the desired functionality can be challenging due to microscopic inhomogeneities that can significantly impact the local optical and electronic properties. Thin lamellas, produced by focused ion beam milling from a homogeneous layer, provide a useful prototype for studying VO2 at the truly microscopic level using a scanning transmission electron microscope (STEM). High-resolution imaging is used to identify structural inhomogeneities while electron energy-loss spectroscopy (EELS) supported by statistical analysis helps to detect V x O y stoichiometries with a reduced oxidation number of vanadium at the areas of thickness below 70 nm. On the other hand, the thicker areas are dominated by vanadium dioxide, where the signatures of the IMT are detected in both core-loss and low-loss EELS experiments with in situ heating. The experimental results are interpreted with ab initio and semi-classical calculations. This work shows that structural inhomogeneities such as pores and cracks present no harm to the desired optical properties of VO2 samples.
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Affiliation(s)
- Jan Krpenský
- Institute of Physical Engineering, Brno University of Technology Technická 2896/2 616 69 Brno Czech Republic
| | - Michal Horák
- Central European Institute of Technology, Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic
| | - Jiří Kabát
- Institute of Physical Engineering, Brno University of Technology Technická 2896/2 616 69 Brno Czech Republic
| | - Jakub Planer
- Central European Institute of Technology, Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic
| | - Peter Kepič
- Central European Institute of Technology, Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic
| | - Vlastimil Křápek
- Institute of Physical Engineering, Brno University of Technology Technická 2896/2 616 69 Brno Czech Republic
- Central European Institute of Technology, Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic
| | - Andrea Konečná
- Institute of Physical Engineering, Brno University of Technology Technická 2896/2 616 69 Brno Czech Republic
- Central European Institute of Technology, Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic
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14
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Samanta S, Park H, Lee C, Jeon S, Cui H, Yao YX, Hwang J, Choi KY, Kim HS. Emergence of flat bands and ferromagnetic fluctuations via orbital-selective electron correlations in Mn-based kagome metal. Nat Commun 2024; 15:5376. [PMID: 38918409 PMCID: PMC11199626 DOI: 10.1038/s41467-024-49674-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 06/17/2024] [Indexed: 06/27/2024] Open
Abstract
Kagome lattice has been actively studied for the possible realization of frustration-induced two-dimensional flat bands and a number of correlation-induced phases. Currently, the search for kagome systems with a nearly dispersionless flat band close to the Fermi level is ongoing. Here, by combining theoretical and experimental tools, we present Sc3Mn3Al7Si5 as a novel realization of correlation-induced almost-flat bands in the kagome lattice in the vicinity of the Fermi level. Our magnetic susceptibility, 27Al nuclear magnetic resonance, transport, and optical conductivity measurements provide signatures of a correlated metallic phase with tantalizing ferromagnetic instability. Our dynamical mean-field calculations suggest that such ferromagnetic instability observed originates from the formation of nearly flat dispersions close to the Fermi level, where electron correlations induce strong orbital-selective renormalization and manifestation of the kagome-frustrated bands. In addition, a significant negative magnetoresistance signal is observed, which can be attributed to the suppression of flat-band-induced ferromagnetic fluctuation, which further supports the formation of flat bands in this compound. These findings broaden a new prospect to harness correlated topological phases via multiorbital correlations in 3d-based kagome systems.
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Affiliation(s)
- Subhasis Samanta
- Department of Semiconductor Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon, 24341, Republic of Korea
- Center for Extreme Quantum Matter and Functionality, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Hwiwoo Park
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Chanhyeon Lee
- Department of Physics, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sungmin Jeon
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Hengbo Cui
- Department of Physics and Astronomy and Institute of Applied Physics, Seoul National University, Seoul, 151-747, Republic of Korea
| | - Yong-Xin Yao
- Ames National Laboratory, U.S. Department of Energy, Ames, IA, 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
| | - Jungseek Hwang
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
| | - Kwang-Yong Choi
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
| | - Heung-Sik Kim
- Department of Semiconductor Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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15
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Kundu AK, Huang X, Seewald E, Ritz E, Pakhira S, Zhang S, Sun D, Turkel S, Shabani S, Yilmaz T, Vescovo E, Dean CR, Johnston DC, Valla T, Birol T, Basov DN, Fernandes RM, Pasupathy AN. Low-energy electronic structure in the unconventional charge-ordered state of ScV 6Sn 6. Nat Commun 2024; 15:5008. [PMID: 38866766 PMCID: PMC11169263 DOI: 10.1038/s41467-024-48883-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 05/14/2024] [Indexed: 06/14/2024] Open
Abstract
Kagome vanadates AV3Sb5 display unusual low-temperature electronic properties including charge density waves (CDW), whose microscopic origin remains unsettled. Recently, CDW order has been discovered in a new material ScV6Sn6, providing an opportunity to explore whether the onset of CDW leads to unusual electronic properties. Here, we study this question using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). The ARPES measurements show minimal changes to the electronic structure after the onset of CDW. However, STM quasiparticle interference (QPI) measurements show strong dispersing features related to the CDW ordering vectors. A plausible explanation is the presence of a strong momentum-dependent scattering potential peaked at the CDW wavevector, associated with the existence of competing CDW instabilities. Our STM results further indicate that the bands most affected by the CDW are near vHS, analogous to the case of AV3Sb5 despite very different CDW wavevectors.
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Affiliation(s)
- Asish K Kundu
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Xiong Huang
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Eric Seewald
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Ethan Ritz
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Santanu Pakhira
- Ames National Laboratory, Iowa State University, Ames, Iowa, 50011, USA
- Department of Physics, Maulana Azad National Institute of Technology, Bhopal, 462003, India
| | - Shuai Zhang
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Dihao Sun
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Simon Turkel
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Sara Shabani
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Turgut Yilmaz
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Elio Vescovo
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Cory R Dean
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - David C Johnston
- Ames National Laboratory, Iowa State University, Ames, Iowa, 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011, USA
| | - Tonica Valla
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
| | - Turan Birol
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Dmitri N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Rafael M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Abhay N Pasupathy
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, 11973, USA.
- Department of Physics, Columbia University, New York, NY, 10027, USA.
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16
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Hazra S, Patil U, Sanvito S. Predicting the One-Particle Density Matrix with Machine Learning. J Chem Theory Comput 2024; 20:4569-4578. [PMID: 38818782 PMCID: PMC11171273 DOI: 10.1021/acs.jctc.4c00042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 06/01/2024]
Abstract
Two of the most widely used electronic-structure theory methods, namely, Hartree-Fock and Kohn-Sham density functional theory, require the iterative solution of a set of Schrödinger-like equations. The speed of convergence of such a process depends on the complexity of the system under investigation, the self-consistent-field algorithm employed, and the initial guess for the density matrix. An initial density matrix close to the ground-state matrix will effectively allow one to cut out many of the self-consistent steps necessary to achieve convergence. Here, we predict the density matrix of Kohn-Sham density functional theory by constructing a neural network that uses only the atomic positions as information. Such a neural network provides an initial guess for the density matrix far superior to that of any other recipes available. Furthermore, the quality of such a neural-network density matrix is good enough for the evaluation of interatomic forces. This allows us to run accelerated ab initio molecular dynamics with little to no self-consistent steps.
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Affiliation(s)
- S. Hazra
- School of Physics and CRANN
Institute, Trinity College, Dublin 2, Ireland
| | - U. Patil
- School of Physics and CRANN
Institute, Trinity College, Dublin 2, Ireland
| | - S. Sanvito
- School of Physics and CRANN
Institute, Trinity College, Dublin 2, Ireland
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17
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Dong Z, Huo M, Li J, Li J, Li P, Sun H, Gu L, Lu Y, Wang M, Wang Y, Chen Z. Visualization of oxygen vacancies and self-doped ligand holes in La 3Ni 2O 7-δ. Nature 2024; 630:847-852. [PMID: 38839959 DOI: 10.1038/s41586-024-07482-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 04/29/2024] [Indexed: 06/07/2024]
Abstract
The recent discovery of superconductivity in La3Ni2O7-δ under high pressure with a transition temperature around 80 K (ref. 1) has sparked extensive experimental2-6 and theoretical efforts7-12. Several key questions regarding the pairing mechanism remain to be answered, such as the most relevant atomic orbitals and the role of atomic deficiencies. Here we develop a new, energy-filtered, multislice electron ptychography technique, assisted by electron energy-loss spectroscopy, to address these critical issues. Oxygen vacancies are directly visualized and are found to primarily occupy the inner apical sites, which have been proposed to be crucial to superconductivity13,14. We precisely determine the nanoscale stoichiometry and its correlation to the oxygen K-edge spectra, which reveals a significant inhomogeneity in the oxygen content and electronic structure within the sample. The spectroscopic results also reveal that stoichiometric La3Ni2O7 has strong charge-transfer characteristics, with holes that are self-doped from Ni sites into O sites. The ligand holes mainly reside on the inner apical O and the planar O, whereas the density on the outer apical O is negligible. As the concentration of O vacancies increases, ligand holes on both sites are simultaneously annihilated. These observations will assist in further development and understanding of superconducting nickelate materials. Our imaging technique for quantifying atomic deficiencies can also be widely applied in materials science and condensed-matter physics.
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Affiliation(s)
- Zehao Dong
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China
| | - Mengwu Huo
- Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-Sen University, Guangzhou, China
| | - Jie Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China
| | - Jingyuan Li
- Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-Sen University, Guangzhou, China
| | - Pengcheng Li
- School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Hualei Sun
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-Sen University, Guangzhou, China
- School of Science, Sun Yat-Sen University, Shenzhen, China
| | - Lin Gu
- School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Yi Lu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
| | - Meng Wang
- Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou, China.
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-Sen University, Guangzhou, China.
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China.
- New Cornerstone Science Laboratory, Frontier Science Center for Quantum Information, Beijing, China.
- Hefei National Laboratory, Hefei, China.
| | - Zhen Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
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18
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Plisson VM, Yao X, Wang Y, Varnavides G, Suslov A, Graf D, Choi ES, Yang HY, Wang Y, Romanelli M, McNamara G, Singh B, McCandless GT, Chan JY, Narang P, Tafti F, Burch KS. Engineering Anomalously Large Electron Transport in Topological Semimetals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2310944. [PMID: 38470991 DOI: 10.1002/adma.202310944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 02/28/2024] [Indexed: 03/14/2024]
Abstract
Anomalous transport of topological semimetals has generated significant interest for applications in optoelectronics, nanoscale devices, and interconnects. Understanding the origin of novel transport is crucial to engineering the desired material properties, yet their orders of magnitude higher transport than single-particle mobilities remain unexplained. This work demonstrates the dramatic mobility enhancements result from phonons primarily returning momentum to electrons due to phonon-electron dominating over phonon-phonon scattering. Proving this idea, proposed by Peierls in 1932, requires tuning electron and phonon dispersions without changing symmetry, topology, or disorder. This is achieved by combining de Haas - van Alphen (dHvA), electron transport, Raman scattering, and first-principles calculations in the topological semimetals MX2 (M = Nb, Ta and X = Ge, Si). Replacing Ge with Si brings the transport mobilities from an order magnitude larger than single particle ones to nearly balanced. This occurs without changing the crystal structure or topology and with small differences in disorder or Fermi surface. Simultaneously, Raman scattering and first-principles calculations establish phonon-electron dominated scattering only in the MGe2 compounds. Thus, this study proves that phonon-drag is crucial to the transport properties of topological semimetals and provides insight to engineer these materials further.
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Affiliation(s)
| | - Xiaohan Yao
- Department of Physics, Boston College, Chestnut Hill, MA, USA
| | - Yaxian Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - George Varnavides
- College of Letters and Science, University of California Los Angeles, Los Angeles, California, 90095, USA
| | - Alexey Suslov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, 32310, USA
| | - David Graf
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, 32310, USA
| | - Eun Sang Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, 32310, USA
| | - Hung-Yu Yang
- Department of Physics, Boston College, Chestnut Hill, MA, USA
| | - Yiping Wang
- Department of Physics, Boston College, Chestnut Hill, MA, USA
| | | | - Grant McNamara
- Department of Physics, Boston College, Chestnut Hill, MA, USA
| | - Birender Singh
- Department of Physics, Boston College, Chestnut Hill, MA, USA
| | - Gregory T McCandless
- Department of Chemistry and Biochemisty, Baylor University, Waco, TX, 76798, USA
| | - Julia Y Chan
- Department of Chemistry and Biochemisty, Baylor University, Waco, TX, 76798, USA
| | - Prineha Narang
- College of Letters and Science, University of California Los Angeles, Los Angeles, California, 90095, USA
| | - Fazel Tafti
- Department of Physics, Boston College, Chestnut Hill, MA, USA
| | - Kenneth S Burch
- Department of Physics, Boston College, Chestnut Hill, MA, USA
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19
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Gopidi HR, Vashist L, Malyi OI. Physics of band-filling correction in defect calculations of solid-state materials. RSC Adv 2024; 14:17675-17683. [PMID: 38836172 PMCID: PMC11148636 DOI: 10.1039/d4ra01528b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 04/16/2024] [Indexed: 06/06/2024] Open
Abstract
In solid-state physics/chemistry, a precise understanding of defect formation and its impact on the electronic properties of wide-bandgap insulators is a cornerstone of modern semiconductor technology. However, complexities arise in the electronic structure theory of defect formation when the latter triggers partial occupation of the conduction/valence band, necessitating accurate post-process correction to the energy calculations. Herein, we dissect these complexities, focusing specifically on the post-process band-filling corrections, a crucial element that often demands thorough treatment in defect formation studies. We recognize the importance of these corrections in maintaining the accuracy of electronic properties predictions in wide-bandgap insulators and their role in reinforcing the importance of a reliable common reference state for defect formation energy calculations. We explored solutions such as aligning deep states and electrostatic potentials, both of which have been used in previous works, showing the effect of band alignment on defect formation energy. Our findings demonstrate that the impact of defect formation on electronic structure (even deep states) can be significantly dependent on the supercell size. We also show that within band-filling calculations, one needs to account for the possible change of electronic structure induced by defect formation, which requires sufficient convergence of electronic structure with supercell size. Thus, this work emphasizes the critical steps to accurately predict defect formation energy and paves the way for future research to overcome these challenges and advance the field with more efficient and reliable predictive models.
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Affiliation(s)
- Harshan Reddy Gopidi
- Centre of Excellence ENSEMBLE3 Sp. z o. o. Wolczynska Str. 133 01-919 Warsaw Poland
| | - Lovelesh Vashist
- Centre of Excellence ENSEMBLE3 Sp. z o. o. Wolczynska Str. 133 01-919 Warsaw Poland
| | - Oleksandr I Malyi
- Qingyuan Innovation Laboratory Quanzhou 362801 P. R. China
- Centre of Excellence ENSEMBLE3 Sp. z o. o. Wolczynska Str. 133 01-919 Warsaw Poland
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20
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Nazir S. Re/Ir@Os-doping induced insulator-to-metal transition in Mott-insulator Ca 2FeOsO 6: octahedral distortion effects. Phys Chem Chem Phys 2024; 26:14384-14392. [PMID: 38712613 DOI: 10.1039/d4cp00746h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Regardless of several investigations to elucidate the ground state of the strongly correlated electron systems in doped Mott-insulators (MIs), the origin of the doping-induced insulator-to-metal transition (IMT) remains a crucial and debatable subject in solid-state physics. Herein, we explore the consequences of Re/Ir-doping at the Os-site (Re/Ir@Os), on the physical properties of the MI ferrimagnetic (FiM) Ca2FeOsO6 double perovskite oxides using density functional theory calculations. The doped structures' solidity is analyzed by computing the defect formation energies in terms of the dopant-rich situation, which confirms their growth credibility at ambient conditions along with mechanical and dynamical stabilities. Various FiM spin-ordering is taken into account in the doped structures to analyze the magnetic ground state, which is FiM-I/FiM-II in the Re/Ir@Os-doped system. Remarkably, an IMT is predicted in the Re/Ir@Os-doped structures, which is due to the admixture of the partially occupied 5d orbitals of these ions. The calculated partial spin magnetic moments (ms) of +4.12, -1.58, -0.75 and +0.88μB on the Fe, Os, Re, and Ir ions, endorse the +3, +5, +5, and +4 states having electronic configurations of t32g↑t02g↓e2g↑e0g↓, t32g↑t02g↓e0g↑e0g↓, t22g↑t02g↓e0g↑e0g↓, t32g↑t22g↓e0g↑e0g↓, respectively. The "+" and "-" signs on the ions ms values, lead the systems into various FiM magnetic ordering. Moreover, the estimated Curie temperature (TC) using the Heisenberg model in the pristine structure is 334 K, which is close to the experimentally observed value of 320 K along with a colossal uniaxial magneto crystalline anisotropy energy constant (K) of 2.95 × 107 erg cm-3 having the easy magnetic axis of the ac-plane ([101]). It is established that TC/K reduces and enhances to 298 K/1.33 × 107 erg cm-3 and 365 K/4.71 × 107 erg cm-3 for the Re@Os and Ir@Os-doped motif due to an increase and decrease in the octahedral distortions compared to that of the pristine system, respectively.
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Affiliation(s)
- S Nazir
- Department of Physics, University of Sargodha, 40100 Sargodha, Pakistan.
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21
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Morishita M, Miyoshi H, Kawasaki H, Yanagita H. Stabilisation of solid-state cubic ammonia confined in a glass substance at ambient temperature under atmospheric pressure. RSC Adv 2024; 14:16128-16137. [PMID: 38769953 PMCID: PMC11103458 DOI: 10.1039/d4ra00229f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 05/08/2024] [Indexed: 05/22/2024] Open
Abstract
Ammonia, a widely available compound, exhibits structural transitions from solid to liquid to gas depending on temperature, pressure, and chemical interactions with adjacent atoms, offering valuable insights into planetary science. It serves as a significant hydrogen storage medium in environmental science, mitigating carbon dioxide emissions from fossil fuels. However, its gaseous form, NH3(g), poses health risks, potentially leading to fatalities. The sublimation pressure (psub) of solid cubic ammonia, NH3(cr), below 195.5 K is minimal. In this study, we endeavoured to stabilise NH3(cr) at room temperature for the first time. Through confinement within a boric acid glass matrix, we successfully synthesised and stabilised cubic crystal NH3(cr) with a lattice constant of 0.5165 nm under atmospheric pressure. Thermodynamic simulations affirmed the stabilisation of NH3(cr), indicating its quasi-equilibrium state based on the estimated standard Gibbs energy of formation, . Despite these advancements, the extraction of H2(g) from NH3(cr) within the boric acid glass matrix remains unresolved. The quest for an external matrix with catalytic capabilities to decompose inner NH3(cr) into H2(g) and N2(g) presents a promising avenue for future research. Achieving stability of the low-temperature phase at ambient conditions could significantly propel exploration in this field.
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Affiliation(s)
- Masao Morishita
- National Institute of Materials Science (NIMS) (Formerly Department of Chemical Engineering and Materials Science), University of Hyogo Japan
| | - Hayate Miyoshi
- Department of Chemical Engineering and Materials Science, University of Hyogo Japan
| | - Haruto Kawasaki
- Department of Chemical Engineering and Materials Science, University of Hyogo Japan
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22
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Soni S, Ahlawat DS, Arora S, Rani M. Analysis of structural, electronic and optical properties of Er-doped rock salt AlN using ab-initio calculations. J Mol Model 2024; 30:160. [PMID: 38713380 DOI: 10.1007/s00894-024-05959-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024]
Abstract
CONTEXT This investigation includes the structural and optoelectronic characteristics of both pure and Er-doped rock salt aluminium nitride (AlN). Upon introducing Er doping into the AlN host, the calculations reveal a rise in the atomic parameter. Incorporating Er into the system leads to enhancements in the static dielectric coefficient ɛ1(0), static reflectivity R(0), as well as static refractive index n(0), at zero frequency. After doping, the peaks of imaginary dielectric tensor, extinction coefficient and absorption coefficient shift towards lower energy levels. Various exchange correlation potentials are incorporated to compare the results of electronic and optical characteristics. METHODS We employed the full potential linearized augmented plane wave (FP-LAPW) approach with WIEN2k code in conjunction with the density functional theory (DFT). To explore the optoelectronic characteristics of both pure as well as doped systems, three distinct exchange correlation potentials are utilized: the Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA), Modified Becke Johnson Generalized Gradient Approximations (mBJ + GGA) and Hubbard potential (GGA + U).
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Affiliation(s)
- Sahil Soni
- Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055, Haryana, India
| | | | - Sandeep Arora
- Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055, Haryana, India
| | - Monika Rani
- Department of Physics, Mohanlal Sukhadia University, Udaipur, 313001, Rajasthan, India
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23
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Tariq S, Alrashdi AO, Al Bahir A, Gilani SMS, Hamioud F, Mubarak AA, Ahmed A, Saad H-E MM. DFT insights into LaFeO 3 with Mn substitution: A promising path to energy-efficient magneto-optical applications. J Comput Chem 2024; 45:843-854. [PMID: 38149650 DOI: 10.1002/jcc.27286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/20/2023] [Accepted: 12/03/2023] [Indexed: 12/28/2023]
Abstract
In recent years, the demand for electronic materials has significantly increased, driven by industrial needs and the pursuit of cost-efficient alternatives. This comprehensive study investigates the effects of Mn substitution on LaFeO3 through the implementation of the GGA approach in density functional theory. The research findings demonstrate remarkable consistency with the experimental outcomes reported in the existing literature pertaining to the studied compounds. However, this study unveils novel insights into the mechanical and optical characteristics of the doped structures, which have not been previously reported. The structural stability is rigorously examined through multiple stability criteria, encompassing structural optimization, tests of elastic stability, and enthalpy of formation calculations. Furthermore, the electronic and optical properties of the compounds exhibit exceptional improvements in conductivity and reflectivity as a result of the doping process. The band structure analysis reveals the presence of a Moss-Burstein shift. Investigation of the magnetic properties indicates an increase in the magnetic moment value due to the Fe-Mn degeneracy resulting from increased Mn content. Mechanical analysis of the elastic moduli B, G, and Y demonstrates an enhanced strength and metal-like conductivity, attributed to the induced anharmonicity. Moreover, the internal strain factor suggests a higher degree of bond flexibility, implying potential applications of these compounds in flexible electronics.
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Affiliation(s)
- Saad Tariq
- Faculty of Science and Technology, Department of Physics, University of Central Punjab, Lahore, Pakistan
| | - Ayash O Alrashdi
- King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Areej Al Bahir
- Chemistry Department, Faculty of Science, King Khalid University, Abha, Saudi Arabia
| | | | - Farida Hamioud
- Nottingham College, Science Faculty, Nottingham, United Kingdom
| | - A A Mubarak
- Physics Department, College of Science and Arts-Rabigh, King Abdulaziz University, Rabigh, Saudi Arabia
| | - Afaq Ahmed
- Centre of Excellence in Solid State Physics, University of the Punjab, Lahore, Pakistan
| | - M Musa Saad H-E
- Department of Physics, College of Science and Arts in Al-Muthnib, Qassim University, Saudi Arabia
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24
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Taj I, Khan MJI, Batool HS, Ahmad J, Yousaf M, Usmani N, Rasheed A. Theoretical investigations of structural, electronic, magnetic, and optical properties of group V (X = V, Nb, Ta) added CeO 2-X materials for optoelectronic applications. J Mol Model 2024; 30:159. [PMID: 38700555 DOI: 10.1007/s00894-024-05958-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 04/29/2024] [Indexed: 05/12/2024]
Abstract
CONTEXT Depletion of natural resources, responsible for energy production, is a serious concern for researchers to develop alternate energy resources or materials. Scientists have proposed various energy materials which are based on semiconductors and their underlying physics. Cerium oxide (CeO2) is a versatile energy material which receives much attention owing to excellent photocatalytic, photonic, thermal stability, and optoelectronic applications. Even though CeO2 exhibited remarkable physical properties, but yet, they can be enhanced upon suitable doping. Focus on current research is to dope group V elements into CeO2 in order to enhance its electronic and optical response. The density of states (DOS) and band gaps of proposed materials are calculated, and significant improvement is noted after applying TB-mbj method. Optical absorption spectra of V/Nb/Ta-doped CeO2 show blueshift and decrease in reflectivity along with the presence of magnetism illustrate potential uses of these materials in future UV optoelectronics, spintronics, sensing, and energy harvesting devices. METHODS This research is based on computational work carried using Wien2k code where PBE-GGA approximation is used to approximate exchange and correlation potentials. Supercells of vanadium/niobium/tantalum-doped CeO2 are constructed, and spin-polarized density of states (DOS) along with optical constant are calculated. TB-mbj method is used to bring improvements in DOS and band gaps of proposed materials. Iterations are conducted using convergence criterion, and non-relativistic calculations are performed.
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Affiliation(s)
- Imran Taj
- Laboratory of Theoretical and Experimental Physics, Institute of Phyiscs (IoP), Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - M Junaid Iqbal Khan
- Laboratory of Theoretical and Experimental Physics, Institute of Phyiscs (IoP), Bahauddin Zakariya University, Multan, 60800, Pakistan.
| | - Hafiza Saima Batool
- Laboratory of Theoretical and Experimental Physics, Institute of Phyiscs (IoP), Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Javed Ahmad
- Laboratory of Theoretical and Experimental Physics, Institute of Phyiscs (IoP), Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Masood Yousaf
- Department of Physics, Division of Science and Technology, University of Education, Lahore, 54770, Pakistan
| | - Nauman Usmani
- Laboratory of Theoretical and Experimental Physics, Institute of Phyiscs (IoP), Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Asif Rasheed
- Laboratory of Theoretical and Experimental Physics, Institute of Phyiscs (IoP), Bahauddin Zakariya University, Multan, 60800, Pakistan
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25
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Jabar A, Maaouni N, Benyoussef S, Bahmad L. Investigation into the physical characteristics of the compounds XBiSe 2 (X = Li, Na or K). J Mol Model 2024; 30:158. [PMID: 38700822 DOI: 10.1007/s00894-024-05960-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 04/30/2024] [Indexed: 05/12/2024]
Abstract
CONTEXT As new materials, the ternary chalcogenides have recently brought scientists' attention. These materials are a novel class of semiconducting chemical compounds. They allow the increase of the photo-conversion efficiency, the performance, and the cheap energy cost. Such materials also provide a wide range of physical and chemical applications. METHODS The used investigation employs Density Functional Theory (DFT) implemented in the Wien2k package to systematically characterize the physical properties of ternary chalcogenide compounds XBiSe2 (X = Li, Na and K). Such method emphasizes their applicability to energy conversion technologies. Scrutinizing their electronic, optical, and thermoelectric properties elucidates the effect of alkali metal substitution on performance metrics. The results not only advance knowledge of these materials' physicochemical behaviors but also reveal their potential for tailored functionalization in next-generation energy and optoelectronic systems, marking a significant stride in material science and application-oriented research.
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Affiliation(s)
- A Jabar
- LPMAT, Faculty of Sciences Aïn Chock, Hassan II University of Casablanca, B.P. 5366, Casablanca, Morocco
- LPHE-MS, Science Faculty, Mohammed V University in Rabat, Rabat, Morocco
| | - N Maaouni
- Laboratory of Condensed Matter and Interdisciplinary Sciences (LaMCScI), Faculty of Sciences, Mohammed V University, Av. Ibn Batouta, B. P. 1014, Rabat, Morocco
| | - S Benyoussef
- Laboratory of Condensed Matter and Interdisciplinary Sciences (LaMCScI), Faculty of Sciences, Mohammed V University, Av. Ibn Batouta, B. P. 1014, Rabat, Morocco
| | - L Bahmad
- Laboratory of Condensed Matter and Interdisciplinary Sciences (LaMCScI), Faculty of Sciences, Mohammed V University, Av. Ibn Batouta, B. P. 1014, Rabat, Morocco.
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26
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Nitika, Ahlawat DS, Arora S. Meta-GGA study of 2D AlN/BN planer heterostructure and performance enhancement via strain engineering. J Mol Model 2024; 30:144. [PMID: 38653800 DOI: 10.1007/s00894-024-05948-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 04/17/2024] [Indexed: 04/25/2024]
Abstract
CONTEXT The 2D AlN/BN planer heterostructure is a promising wide band gap semiconductor, but systematic studies of its bandgap and optical characteristics under applied strain are scarce. Here, the engineering property of 2D AlN/BN comprising bandgap nature transition and optical absorption capability (from unstrained to strained) have been investigated using density functional theory calculations. The formation energy calculations confirm the stability of the simulated nanoheterostructure. The electronic band structure calculations demonstrate that nanoheterostructure is an indirect bandgap material with a large bandgap of 5.26 eV, which can be modified effectively by applying strain. According to the calculations, the transition from indirect to direct band gap behavior has been observed at +15% biaxial strain with 2.71 eV band gap energy. Meanwhile, calculations for optical absorption and dielectric function reveal that the system has significant absorption peaks in the ultraviolet region which are very sensitive to applied strain. As strain increases, the first absorption peaks are shifted towards a lower energy range from 5.73 eV (Ꜫ= 0 %) to 3.76 eV (Ꜫ = +15%), which features an enhancement of optical absorption for solar and solar-blind regions. Furthermore, we determined that the band edge positions in 2D AlN/BN straddled the water redox potential under strain, indicating its effectiveness as a proficient photocatalyst. These characteristics make 2D AlN/BN planer nanoheterostructure a promising candidate for applications in optoelectronics and photocatalytic water splitting performance. METHODS First principles computations based on density functional theory were employed to carry out all the calculations with a self-consistent approach. For solving the Kohn-Sham equations, the first principles dependent full-potential linearized augmented plane wave scheme were adopted. For addressing the exchange-correlation effects, the generalized gradient approximation of PBEsol functional was used. To prevent interaction between the periodic images, we have inserted a vacuum region of 10 Å in the z-direction. Non-negligible weak dispersion corrections in nanoheterostructure were considered by using the DFT-D3 method of Grimme's. The locally modified Becke-Johnson (lmBJ) exchange potential has also been applied to compute electronic and optical properties in this research to obtain more accurate information.
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Affiliation(s)
- Nitika
- Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055(Hry.), India
| | | | - Sandeep Arora
- Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055(Hry.), India
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27
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Zhao M, Wang Z, Liu L, Wang C, Liu CY, Yang F, Wu H, Gao C. Atomic-scale visualization of the interlayer Rydberg exciton complex in moiré heterostructures. Nat Commun 2024; 15:3414. [PMID: 38649358 PMCID: PMC11035671 DOI: 10.1038/s41467-024-47770-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 04/10/2024] [Indexed: 04/25/2024] Open
Abstract
Excitonic systems, facilitated by optical pumping, electrostatic gating or magnetic field, sustain composite particles with fascinating physics. Although various intriguing excitonic phases have been revealed via global measurements, the atomic-scale accessibility towards excitons has yet to be established. Here, we realize the ground-state interlayer exciton complexes through the intrinsic charge transfer in monolayer YbCl3/graphite heterostructure. Combining scanning tunneling microscope and theoretical calculations, the excitonic in-gap states are directly profiled. The out-of-plane excitonic charge clouds exhibit oscillating Rydberg nodal structure, while their in-plane arrangements are determined by moiré periodicity. Exploiting the tunneling probe to reflect the shape of charge clouds, we reveal the principal quantum number hierarchy of Rydberg series, which points to an excitonic energy-level configuration with unusually large binding energy. Our results demonstrate the feasibility of mapping out the charge clouds of excitons microscopically and pave a brand-new way to directly investigate the nanoscale order of exotic correlated phases.
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Affiliation(s)
- Meng Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Zhongjie Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200232, China.
| | - Lu Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai, 200438, China
| | - Chunzheng Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Cheng-Yen Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
- Shanghai Qi Zhi Institute, Shanghai, 200232, China
| | - Fang Yang
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Songhu Rd. 2005, Shanghai, 200438, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, 201210, China
| | - Hua Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200232, China.
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai, 200438, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - Chunlei Gao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200232, China.
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Songhu Rd. 2005, Shanghai, 200438, China.
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, 201210, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China.
- Shanghai Branch, Hefei National Laboratory, Shanghai, 201315, China.
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28
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Ramirez D, Menezes LT, Kleinke H. Synthesis and Transport Properties of ZnSnP 2-yAs y Chalcopyrite Solid Solutions. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1712. [PMID: 38673070 PMCID: PMC11050980 DOI: 10.3390/ma17081712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/02/2024] [Accepted: 04/07/2024] [Indexed: 04/28/2024]
Abstract
This work focuses on the synthesis and properties of quaternary ZnSnP2-yAsy chalcopyrite solid solutions. Full miscibility of the solid solution is achieved using ball milling followed by hot press sintering. The measured electrical conductivity increases substantially with As substitution from 0.03 S cm-1 for ZnSnP2 to 10.3 S cm-1 for ZnSnAs2 at 715 K. Band gaps calculated from the activation energies show a steady decrease with increasing As concentration from 1.4 eV for ZnSnP2 to 0.7 eV for ZnSnAs2. The Seebeck coefficient decreases significantly with As substitution from nearly 1000 μV K-1 for ZnSnP2 to -100 μV K-1 for ZnSnAs2 at 650 K. Thermal conductivity is decreased for the solid solutions due to alloy phonon scattering, compared to the end members with y = 0 and y = 2, with the y = 0.5 and y = 1.0 samples exhibiting the lowest values of 1.4 W m-1 K-1 at 825 K. Figure of merit values are increased for the undoped solid solutions at lower temperatures when compared to the end members due to the decreased thermal conductivity, with the y = 0.5 sample reaching zT = 1.6 × 10-3 and y = 1 reaching 2.1 × 10-3 at 700 K. The largest values of the figure of merit zT for the undoped series was found for y = 2 with zT = 2.8 × 10-3 at 700 K due to the increasing n-type Seebeck coefficient. Boltztrap calculations reveal that p-doping could yield zT values above unity at 800 K in case of ZnSnAs2, comparable with ZnSnP2.
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Affiliation(s)
| | | | - Holger Kleinke
- Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (D.R.); (L.T.M.)
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29
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Zhang Y, Gao B, Lepage D, Tong Y, Wang P, Xia W, Niu J, Feng Y, Chen H, Qian H. Large second-order susceptibility from a quantized indium tin oxide monolayer. NATURE NANOTECHNOLOGY 2024; 19:463-470. [PMID: 38168927 DOI: 10.1038/s41565-023-01574-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 11/13/2023] [Indexed: 01/05/2024]
Abstract
Due to their high optical transparency and electrical conductivity, indium tin oxide thin films are a promising material for photonic circuit design and applications. However, their weak optical nonlinearity has been a substantial barrier to nonlinear signal processing applications. In this study, we show that an atomically thin (~1.5 nm) indium tin oxide film in the form of an air/indium tin oxide/SiO2 quantum well exhibits a second-order susceptibility χ2 of ~1,800 pm V-1. First-principles calculations and quantum electrostatic modelling point to an electronic interband transition resonance in the asymmetric potential energy of the quantum well as the reason for this large χ2 value. As the χ2 value is more than 20 times higher than that of the traditional nonlinear LiNbO3 crystal, our indium tin oxide quantum well design can be an important step towards nonlinear photonic circuit applications.
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Affiliation(s)
- Yiyun Zhang
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China
| | - Bingtao Gao
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China
| | - Dominic Lepage
- Institut Quantique, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Yuanbiao Tong
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Pan Wang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Wendi Xia
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China
| | - Junru Niu
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China
| | - Yiming Feng
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China
| | - Hongsheng Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China.
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China.
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China.
| | - Haoliang Qian
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China.
- International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China.
- Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China.
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30
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Kim M, Choi S, Brito WH, Kotliar G. Orbital-Selective Mott Transition Effects and Nontrivial Topology of Iron Chalcogenide. PHYSICAL REVIEW LETTERS 2024; 132:136504. [PMID: 38613298 DOI: 10.1103/physrevlett.132.136504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 03/07/2024] [Indexed: 04/14/2024]
Abstract
The iron-based superconductor FeSe_{1-x}Te_{x} has recently gained significant attention as a host of two distinct physical phenomena: (i) Majorana zero modes that can serve as potential topologically protected qubits, and (ii) a realization of the orbital-selective Mott transition. In this Letter, we connect these two phenomena and provide new insights into the interplay between strong electronic correlations and nontrivial topology in FeSe_{1-x}Te_{x}. Using linearized quasiparticle self-consistent GW plus dynamical mean-field theory, we show that the topologically protected Dirac surface state has substantial Fe(d_{xy}) character. The proximity to the orbital-selective Mott transition plays a dual role: it facilitates the appearance of the topological surface state by bringing the Dirac cone close to the chemical potential but destroys the Z_{2} topological superconductivity when the system is too close to the orbital-selective Mott phase. We derive a reduced effective Hamiltonian that describes the topological band. Its parameters capture all the chemical trends found in the first principles calculation. Our findings provide a framework for further study of the interplay between strong electronic correlations and nontrivial topology in other iron-based superconductors.
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Affiliation(s)
- Minjae Kim
- Korea Institute for Advanced Study, Seoul 02455, South Korea
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Sangkook Choi
- Korea Institute for Advanced Study, Seoul 02455, South Korea
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Walber Hugo Brito
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Departamento de Física, Universidade Federal de Minas Gerais, C. P. 702, 30123-970 Belo Horizonte, MG, Brazil
| | - Gabriel Kotliar
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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31
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Celiberti L, Fiore Mosca D, Allodi G, Pourovskii LV, Tassetti A, Forino PC, Cong R, Garcia E, Tran PM, De Renzi R, Woodward PM, Mitrović VF, Sanna S, Franchini C. Spin-orbital Jahn-Teller bipolarons. Nat Commun 2024; 15:2429. [PMID: 38499529 PMCID: PMC11258125 DOI: 10.1038/s41467-024-46621-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 03/04/2024] [Indexed: 03/20/2024] Open
Abstract
Polarons and spin-orbit (SO) coupling are distinct quantum effects that play a critical role in charge transport and spin-orbitronics. Polarons originate from strong electron-phonon interaction and are ubiquitous in polarizable materials featuring electron localization, in particular 3d transition metal oxides (TMOs). On the other hand, the relativistic coupling between the spin and orbital angular momentum is notable in lattices with heavy atoms and develops in 5d TMOs, where electrons are spatially delocalized. Here we combine ab initio calculations and magnetic measurements to show that these two seemingly mutually exclusive interactions are entangled in the electron-doped SO-coupled Mott insulator Ba2Na1-xCaxOsO6 (0 < x < 1), unveiling the formation of spin-orbital bipolarons. Polaron charge trapping, favoured by the Jahn-Teller lattice activity, converts the Os 5d1 spin-orbital Jeff = 3/2 levels, characteristic of the parent compound Ba2NaOsO6 (BNOO), into a bipolaron 5d2 Jeff = 2 manifold, leading to the coexistence of different J-effective states in a single-phase material. The gradual increase of bipolarons with increasing doping creates robust in-gap states that prevents the transition to a metal phase even at ultrahigh doping, thus preserving the Mott gap across the entire doping range from d1 BNOO to d2 Ba2CaOsO6 (BCOO).
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Affiliation(s)
- Lorenzo Celiberti
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, 1090, Vienna, Austria
- Department of Physics and Astronomy, Università di Bologna, 40127, Bologna, Italy
| | - Dario Fiore Mosca
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, 1090, Vienna, Austria
- CPHT, CNRS, École polytechnique, Institut Polytechnique de Paris, 91120, Palaiseau, France
- Collège de France, Université PSL, 11 place Marcelin Berthelot, 75005, Paris, France
| | - Giuseppe Allodi
- Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124, Parma, Italy
| | - Leonid V Pourovskii
- CPHT, CNRS, École polytechnique, Institut Polytechnique de Paris, 91120, Palaiseau, France
- Collège de France, Université PSL, 11 place Marcelin Berthelot, 75005, Paris, France
| | - Anna Tassetti
- Department of Physics and Astronomy, Università di Bologna, 40127, Bologna, Italy
| | | | - Rong Cong
- Department of Physics, Brown University, Providence, RI, 02912, USA
| | - Erick Garcia
- Department of Physics, Brown University, Providence, RI, 02912, USA
| | - Phuong M Tran
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Roberto De Renzi
- Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124, Parma, Italy
| | - Patrick M Woodward
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Vesna F Mitrović
- Department of Physics, Brown University, Providence, RI, 02912, USA
| | - Samuele Sanna
- Department of Physics and Astronomy, Università di Bologna, 40127, Bologna, Italy
| | - Cesare Franchini
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, 1090, Vienna, Austria.
- Department of Physics and Astronomy, Università di Bologna, 40127, Bologna, Italy.
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32
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Menezes LT, Gage E, Assoud A, Kleinke H. Comparative Analysis of the Crystal Structures and Physical Properties of the Complex Group 14 Selenides Sr 8Ge 4Se 17 and Ba 8Sn 4Se 17. Inorg Chem 2024; 63:4982-4988. [PMID: 38452752 DOI: 10.1021/acs.inorgchem.3c04303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
During our group's continued exploration of group 14 chalcogenides, we discovered two new compounds, Sr8Ge4Se17 and Ba8Sn4Se17. Both compounds have an 8:4:17 stoichiometric ratio but adopt different centrosymmetric crystal structures. Sr8Ge4Se17 crystallizes in the triclinic P1̅ space group with a = 11.8429(18) Å, b = 12.172(3) Å, c = 13.624(3) Å, α = 114.472(5)0, β = 97.396(5)0, γ = 107.040(5)0, and Z = 2. Ba8Sn4Se17 crystallizes in the monoclinic C2/c space group with a = 47.286(3) Å, b = 12.6294(5) Å, c = 25.7303(15) Å, β = 104.585(5)0, and Z = 16. The unit cell of Ba8Sn4Se17 is approximately eight times larger than the unit cell of Sr8Ge4Se17, which is a consequence of the differently aligned tetrahedra, resulting in a quadrupled a axis, unchanged b axis, and doubled c axis. The lattice parameters and atomic coordinates were finalized via Rietveld refinements on data collected at a high-energy synchrotron beamline. Both compounds are semiconductors with band gaps in the visible region. Sr8Ge4Se17 and Ba8Sn4Se17 have optical band gaps of 1.88 and 1.93 eV, respectively. Both compounds have remarkably low thermal conductivities owing to their low symmetries and large unit cells. The minimum experimental thermal conductivity values of Sr8Ge4Se17 and Ba8Sn4Se17 are 0.45 W m-1 K-1 at 321 K and 0.31 W m-1 K-1 at 324 K, respectively.
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Affiliation(s)
- Luke T Menezes
- Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Eliana Gage
- Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Abdeljalil Assoud
- Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Holger Kleinke
- Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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Imasato K, Miyazaki H, Sauerschnig P, Johari KK, Ishida T, Yamamoto A, Ohta M. Achieving Compatible p/n-Type Half-Heusler Compositions in Valence Balanced/Unbalanced Mg 1-xV xNiSb. ACS APPLIED MATERIALS & INTERFACES 2024; 16:11637-11645. [PMID: 38408287 DOI: 10.1021/acsami.3c16324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
In thermoelectric and other inorganic materials research, the significance of half-Heusler (HH) compositions following the 18-electron rule has drawn interest in developing and exploiting the potential of intermetallic compounds. For the fabrication of thermoelectric modules, in addition to high-performance materials, having both p- and n-type materials with compatible thermal expansion coefficients is a prerequisite for module development. In this work, the p-type to n-type transition of valence balanced/unbalanced HH composition of Mg1-xVxNiSb was demonstrated by changing the Mg:V chemical ratio. The Seebeck coefficient and power factor of Ti-doped Mg0.57V0.33Ti0.1NiSb are -130 μV K-1 and 0.4 mW m-1 K-2 at 400 K, respectively. In addition, the reduced lattice thermal conductivity (κL < 2.5 W m-1 K-1 at 300 K) of n-type compositions was reported to be much smaller than κL of conventional HH materials. As high thermal conductivity has long been an issue for HH materials, the synthesis of p- and n-type Mg1-xVxNiSb compositions with low lattice thermal conductivity is a promising strategy for producing high-performance HH compounds. Achieving both p- and n-type materials from similar parent composition enabled us to fabricate a thermoelectric module with maximum output power Pmax ∼ 63 mW with a temperature difference of 390 K. This finding supports the benefit of exploring the huge compositional space of valence balanced/unbalanced quaternary HH compositions for further development of thermoelectric devices.
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Affiliation(s)
- Kazuki Imasato
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
- Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
| | - Hidetoshi Miyazaki
- Department of Physical Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
| | - Philipp Sauerschnig
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
| | - Kishor Kumar Johari
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
| | - Takao Ishida
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
| | - Atsushi Yamamoto
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
| | - Michihiro Ohta
- Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
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34
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ÖZDEMİR EG. Ab-initio Calculations of the Half-metallic Ferromagnetic New Variant Perovskites Li2CrO6 and Li2CuO6. GAZI UNIVERSITY JOURNAL OF SCIENCE 2024. [DOI: 10.35378/gujs.1073140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The half-metallic calculations of new variant perovskites Li2CrO6 and Li2CuO6 were carried out by using WIEN2k computational code. First, the ferromagnetic (FM) and non-magnetic (NM) phases were compared, and FM phases were obtained energetically more stable. The equilibrium lattice constants were obtained as 7.63 Å and 7.66 Å for Li2CrO6 and Li2CuO6, respectively. Second, the electronic calculations were performed, and the semiconduction properties were seen in spin-up states while spin-down states showed metallic nature. The band gaps were obtained as 1.806 eV and 1.177 eV for Li2CrO6 and Li2CuO6, respectively. Since variant perovskites Li2CrO6 and Li2CuO6 showed 100% spin polarizations, these were obtained as true half-metallic ferromagnetic materials. Then the total magnetic moments were obtained as 4.00 μB/f.u., 5.00 μB/f.u. When both the electronic and magnetic properties of the compounds are examined, the variant perovskites Li2CrO6 and Li2CuO6 are suitable materials for spintronics applications.
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Cui J, Sha H, Yang W, Yu R. Antiferromagnetic imaging via ptychographic phase retrieval. Sci Bull (Beijing) 2024; 69:466-472. [PMID: 38161093 DOI: 10.1016/j.scib.2023.12.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/27/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024]
Abstract
Antiferromagnetic imaging is critical for understanding and optimizing the properties of antiferromagnetic materials and devices. Despite the widespread use of high-energy electrons for atomic-scale imaging, they have low sensitivity to spin textures. Typically, the magnetic contribution to the phase of a high-energy electron wave is weaker than one percent of the electrostatic potential. Here, we demonstrate direct imaging of antiferromagnetic lattice through precise phase retrieval via electron ptychography, paving the way for magnetic lattice imaging of antiferromagnetic materials and devices.
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Affiliation(s)
- Jizhe Cui
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China; State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084, China
| | - Haozhi Sha
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China; State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084, China
| | - Wenfeng Yang
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China; State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084, China
| | - Rong Yu
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China; State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084, China.
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Siebenhofer M, Nenning A, Rameshan C, Blaha P, Fleig J, Kubicek M. Engineering surface dipoles on mixed conducting oxides with ultra-thin oxide decoration layers. Nat Commun 2024; 15:1730. [PMID: 38409206 PMCID: PMC11258326 DOI: 10.1038/s41467-024-45824-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 02/01/2024] [Indexed: 02/28/2024] Open
Abstract
Improving materials for energy conversion and storage devices is deeply connected with an optimization of their surfaces and surface modification is a promising strategy on the way to enhance modern energy technologies. This study shows that surface modification with ultra-thin oxide layers allows for a systematic tailoring of the surface dipole and the work function of mixed ionic and electronic conducting oxides, and it introduces the ionic potential of surface cations as a readily accessible descriptor for these effects. The combination of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) illustrates that basic oxides with a lower ionic potential than the host material induce a positive surface charge and reduce the work function of the host material and vice versa. As a proof of concept that this strategy is widely applicable to tailor surface properties, we examined the effect of ultra-thin decoration layers on the oxygen exchange kinetics of pristine mixed conducting oxide thin films in very clean conditions by means of in-situ impedance spectroscopy during pulsed laser deposition (i-PLD). The study shows that basic decorations with a reduced surface work function lead to a substantial acceleration of the oxygen exchange on the surfaces of diverse materials.
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Affiliation(s)
- Matthäus Siebenhofer
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria.
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | | | - Peter Blaha
- Institute of Materials Chemistry, TU Wien, Vienna, Austria
| | - Jürgen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Markus Kubicek
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria.
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Nazir S. Insulator-to-metal transition, magnetic anisotropy, and improved TC in a ferrimagnetic La 2CoIrO 6: strain influence. Phys Chem Chem Phys 2024; 26:5002-5009. [PMID: 38258460 DOI: 10.1039/d3cp04755e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The elegant interactions between Coulomb repulsion and spin-orbit coupling in Ir-based double perovskite oxides (DPO) normally induce peculiar magnetic behavior. Herein, we investigate the effect of the development of biaxial [110] strain on the formation energetics, and electronic and magnetic properties of the La2CoIrO6 DPO employing density functional theory calculations. Our results reveal that the unstrained motif is a Mott-insulator achieving an energy band gap of 0.35 eV with a ferrimagnetic (FiM) ground state, which essentially arises due to anti-ferromagnetic (AFM) coupling between the half-occupied Co t2g and partially occupied Ir t2g/empty eg orbitals via oxygen 2p states. Along with this, it is found that [001] (c-axis) is the easy magnetic axis, which results in 12.5 meV total energy per u.c., obtaining a large anisotropy constant of 0.8 × 108 erg cm-3. The computed partial spin-magnetic moments on the Co/Ir ion are 2.64/-0.46 μB, where the negative sign on the Ir ion moment confirms the AFM interactions between them. Additionally, the t2g/eg and t2g orbital characteristics of Co2+ and Ir4+ ions are visible in the spin-magnetization density isosurfaces plot, respectively. Likewise, the estimated Curie temperature (TC) using the Heisenberg model is 104 K, which is in agreement with the experimentally observed value of 94/97 K. Interestingly, an insulator-to-metal transition is achieved at a critical compressive strain of -6% with a robust FiM state, where the Co 3dxy and Ir 5dx2-y2 orbitals are mainly responsible for metallicity. Simultaneously, the magnetocrystalline anisotropy energy and TC can be sufficiently enhanced by applying compressive strain due to enhancement in the structural distortions. So this work suggested that the strain strategy is an efficient approach to tuning the properties of the compounds for their feasible realization in spintronics.
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Affiliation(s)
- S Nazir
- Department of Physics, University of Sargodha, 40100 Sargodha, Pakistan.
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38
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Pandey P, Pandey SK. Ab initioinvestigation of the lattice dynamics and thermophysical properties of BCC vanadium and niobium. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:165602. [PMID: 38190735 DOI: 10.1088/1361-648x/ad1bf4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 01/08/2024] [Indexed: 01/10/2024]
Abstract
In the present work, we have performed the phonon dispersion calculations of body-centered cubic vanadium (V) and niobium (Nb) with the supercell approach using different supercell size. Using DFT method, the calculated phonon spectra of V and Nb are found to be in a good agreement with the available experimental data. Our calculated results show a 'dip'-like feature in the longitudinal acoustic phonon mode along the Γ-H high symmetric path for both transition metals in the case of supercell size4×4×4. However, in supercell size2×2×2and3×3×3, the 'dip'-like feature is not clearly visible. In addition to this, thermodynamical properties are also computed, which compare well with the experimental data. Apart from this, the phonon lifetime due to electron-phonon interactions (τephph) and phonon-phonon interactions (PPIs) (τphph) are calculated. The effect of PPIs is studied by computing the average phonon lifetime for all acoustic branches. The value ofτephphof V (Nb) is found to be 23.16 (24.70)×10-15s at 100 K, which gets decreased to 1.51 (1.85)×10-15s at 1000 K. Theτphphof V (Nb) is found to be 8.59 (18.09)×10-12and 0.83 (1.76)×10-12s at 100 and 1000 K, respectively. Nextly, the lattice thermal conductivity is computed using linearized phonon Boltzmann equation. The present work suggests that studying the variation of phonon dispersion with supercell size is crucial for understanding the phonon properties of solids accurately.
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Affiliation(s)
- Prakash Pandey
- School of Physical Sciences, Indian Institute of Technology Mandi, Kamand 175075, India
| | - Sudhir K Pandey
- School of Mechanical and Materials Engineering, Indian Institute of Technology Mandi, Kamand 175075, India
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39
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Lee S, Lee S, Jung S, Jung J, Kim D, Lee Y, Seok B, Kim J, Park BG, Šmejkal L, Kang CJ, Kim C. Broken Kramers Degeneracy in Altermagnetic MnTe. PHYSICAL REVIEW LETTERS 2024; 132:036702. [PMID: 38307068 DOI: 10.1103/physrevlett.132.036702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/14/2023] [Indexed: 02/04/2024]
Abstract
Altermagnetism is a newly identified fundamental class of magnetism with vanishing net magnetization and time-reversal symmetry broken electronic structure. Probing the unusual electronic structure with nonrelativistic spin splitting would be a direct experimental verification of an altermagnetic phase. By combining high-quality film growth and in situ angle-resolved photoemission spectroscopy, we report the electronic structure of an altermagnetic candidate, α-MnTe. Temperature-dependent study reveals the lifting of Kramers degeneracy accompanied by a magnetic phase transition at T_{N}=267 K with spin splitting of up to 370 meV, providing direct spectroscopic evidence for altermagnetism in MnTe.
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Affiliation(s)
- Suyoung Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Sangjae Lee
- The Research Institute of Basic Sciences, Seoul National University, Seoul 08826, Korea
| | - Saegyeol Jung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Jiwon Jung
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Yeonjae Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Byeongjun Seok
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Jaeyoung Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Byeong Gyu Park
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Libor Šmejkal
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - Chang-Jong Kang
- Department of Physics, Chungnam National University, Daejeon 34134, Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
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40
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Lucrezi R, Ferreira PP, Aichhorn M, Heil C. Temperature and quantum anharmonic lattice effects on stability and superconductivity in lutetium trihydride. Nat Commun 2024; 15:441. [PMID: 38199988 PMCID: PMC10781996 DOI: 10.1038/s41467-023-44326-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 12/08/2023] [Indexed: 01/12/2024] Open
Abstract
In this work, we resolve conflicting experimental and theoretical findings related to the dynamical stability and superconducting properties of [Formula: see text]-LuH3, which was recently suggested as the parent phase harboring room-temperature superconductivity at near-ambient pressures. Including temperature and quantum anharmonic lattice effects in our calculations, we demonstrate that the theoretically predicted structural instability of the [Formula: see text] phase near ambient pressures is suppressed for temperatures above 200 K. We provide a p-T phase diagram for stability up to pressures of 6 GPa, where the required temperature for stability is reduced to T > 80 K. We also determine the superconducting critical temperature Tc of [Formula: see text]-LuH3 within the Migdal-Eliashberg formalism, using temperature- and quantum-anharmonically-corrected phonon dispersions, finding that the expected Tc for electron-phonon mediated superconductivity is in the range of 50-60 K, i.e., well below the temperatures required to stabilize the lattice. When considering moderate doping based on rigidly shifting the Fermi level, Tc decreases for both hole and electron doping. Our results thus provide evidence that any observed room-temperature superconductivity in pure or doped [Formula: see text]-LuH3, if confirmed, cannot be explained by a conventional electron-phonon mediated pairing mechanism.
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Affiliation(s)
- Roman Lucrezi
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - Pedro P Ferreira
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
- Universidade de São Paulo, Escola de Engenharia de Lorena, DEMAR, 12612-550, Lorena, Brazil
| | - Markus Aichhorn
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - Christoph Heil
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria.
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41
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Rahimi S, Jalali-Asadabadi S, Blaha P, Jalali-Asadabadi F. Nonzero spontaneous electric polarization in metals: novel predictive methods and applications. Sci Rep 2024; 14:672. [PMID: 38182613 PMCID: PMC10770415 DOI: 10.1038/s41598-023-49463-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 12/08/2023] [Indexed: 01/07/2024] Open
Abstract
Ferroelectricity in metals has advanced since the initial discovery of nonmagnetic ferroelectric-like metal LiOsO[Formula: see text], anchored in the Anderson and Blount prediction. However, evaluating the spontaneous electric polarization (SEP) of this metal has been hindered by experimental and theoretical obstacles. The experimental challenge arises from difficulties in switching polarization using an external electric field, while the theoretical limitation lies in existing methods applicable only to nonmetals. Zabalo and Stengel (Phys Rev Lett 126:127601, 2021, https://doi.org/10.1103/PhysRevLett.126.127601 ) addressed the experimental obstacle by proposing flexoelectricity as an alternative for practical polarization switching in LiOsO[Formula: see text], which requires a critical bending radius similar to BaTiO[Formula: see text]. In this study, we focus on resolving the theoretical obstacle by modifying the Berry phase and Wannier functions approaches within density functional theory plus modern theory of polarization. By employing these modifications, we calculate the SEP of LiOsO[Formula: see text], comparable to the polarization of BaTiO[Formula: see text]. We validate our predictions using various ways. This study confirms the coexistence of ferroelectricity and metallicity in this new class of ferroelectric-like metals. Moreover, by addressing the theoretical limitation and providing new insights into polarization properties, our study complements the experimental flexoelectricity proposal and opens avenues for further exploration and manipulation of polarization characteristics. The developed approaches, incorporating modified Berry phase and Wannier function techniques, offer promising opportunities for studying and designing novel materials, including bio- and nano-ferroelectric-like metals. This study contributes to the advancement of ferroelectricity in metals and provides a foundation for future research in this exciting field.
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Affiliation(s)
- Shahrbano Rahimi
- Department of Physics, Faculty of Physics, University of Isfahan (UI), Hezar Jerib Avenue, Isfahan, 81746-73441, Iran
| | - S Jalali-Asadabadi
- Department of Physics, Faculty of Physics, University of Isfahan (UI), Hezar Jerib Avenue, Isfahan, 81746-73441, Iran.
| | - Peter Blaha
- Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/165-TC, 1060, Vienna, Austria
| | - Farhad Jalali-Asadabadi
- Department of Physics, Faculty of Physics, University of Isfahan (UI), Hezar Jerib Avenue, Isfahan, 81746-73441, Iran
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42
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Samanta S, Hong D, Kim HS. Electronic Structures of Kitaev Magnet Candidates RuCl 3 and RuI 3. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:9. [PMID: 38202464 PMCID: PMC10780606 DOI: 10.3390/nano14010009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024]
Abstract
Layered honeycomb magnets with strong atomic spin-orbit coupling at transition metal sites have been intensively studied for the search of Kitaev magnetism and the resulting non-Abelian braiding statistics. α-RuCl3 has been the most promising candidate, and there have been several reports on the realization of sibling compounds α-RuBr3 and α-RuI3 with the same crystal structure. Here, we investigate correlated electronic structures of α-RuCl3 and α-RuI3 by employing first-principles dynamical mean-field theory. Our result provides a valuable insight into the discrepancy between experimental and theoretical reports on transport properties of α-RuI3, and suggests a potential realization of correlated flat bands with strong spin-orbit coupling and a quantum spin-Hall insulating phase in α-RuI3.
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Affiliation(s)
- Subhasis Samanta
- Department of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea; (S.S.); (D.H.)
| | - Dukgeun Hong
- Department of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea; (S.S.); (D.H.)
| | - Heung-Sik Kim
- Department of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea; (S.S.); (D.H.)
- Institute of Quantum Convergence and Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
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Parveen A, Abbas Z, Hussain S, Shaikh SF, Aslam M, Jung J. Theoretical Justification of Structural, Magnetoelectronic and Optical Properties in QFeO 3 (Q = Bi, P, Sb): A First-Principles Study. MICROMACHINES 2023; 14:2251. [PMID: 38138420 PMCID: PMC10745569 DOI: 10.3390/mi14122251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/29/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023]
Abstract
One of the primary objectives of scientific research is to create state-of-the-art multiferroic (MF) materials that exhibit interconnected properties, such as piezoelectricity, magnetoelectricity, and magnetostriction, and remain functional under normal ambient temperature conditions. In this study, we employed first-principles calculations to investigate how changing pnictogen elements affect the structural, electronic, magnetic, and optical characteristics of QFeO3 (Q = Bi, P, SB). Electronic band structures reveal that BiFeO3 is a semiconductor compound; however, PFeO3 and SbFeO3 are metallic. The studied compounds are promising for spintronics, as they exhibit excellent magnetic properties. The calculated magnetic moments decreased as we replaced Bi with SB and P in BiFeO3. A red shift in the values of ε2(ω) was evident from the presented spectra as we substituted Bi with Sb and P in BiFeO3. QFeO3 (Q = Bi, P, SB) showed the maximum absorption of incident photons in the visible region. The results obtained from calculating the optical parameters suggest that these materials have a strong potential to be used in photovoltaic applications.
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Affiliation(s)
- Amna Parveen
- College of Pharmacy, Gachon University, No. 191, Hambakmeoro, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Zeesham Abbas
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea; (Z.A.); (S.H.)
| | - Sajjad Hussain
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea; (Z.A.); (S.H.)
| | - Shoyebmohamad F. Shaikh
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Muhammad Aslam
- Institute of Physics and Technology, Ural Federal University, Mira Str. 19, 620002 Yekaterinburg, Russia
| | - Jongwan Jung
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea; (Z.A.); (S.H.)
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Jeon J, Jang J, Kim H, Park T, Kim D, Moon S, Kim JS, Shim JH, Min H, Choi E. Optical Transitions of a Single Nodal Ring in SrAs_{3}: Radially and Axially Resolved Characterization. PHYSICAL REVIEW LETTERS 2023; 131:236903. [PMID: 38134786 DOI: 10.1103/physrevlett.131.236903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/12/2023] [Accepted: 11/08/2023] [Indexed: 12/24/2023]
Abstract
SrAs_{3} is a unique nodal-line semimetal that contains only a single nodal ring in the Brillouin zone, uninterrupted by any trivial bands near the Fermi energy. We performed axis-resolved optical reflection measurements on SrAs_{3} and observed that the optical conductivity exhibits flat absorption up to 129 meV in both the radial and axial directions, confirming the robustness of the universal power-law behavior of the nodal ring. The axis-resolved optical conductivity, in combination with theoretical calculations, further reveals fundamental properties beyond the flat absorption, including the overlap energy of the topological bands, the spin-orbit coupling gap along the nodal ring, and the geometric properties of the nodal ring such as the average ring radius, ring ellipticity, and velocity anisotropy. In addition, our temperature-dependent measurements revealed a spectral weight transfer between intraband and interband transitions, indicating a possible violation of the optical sum rule within the measured energy range.
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Affiliation(s)
- Jiwon Jeon
- Natural Science Research Institute, University of Seoul, Seoul 02504, Korea
- Physics Department, University of Seoul, Seoul 02504, Korea
| | - Jiho Jang
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Hoil Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Taesu Park
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Dongwook Kim
- Department of Physics, Hanyang University, Seoul 04763, Korea
| | - Soonjae Moon
- Department of Physics, Hanyang University, Seoul 04763, Korea
| | - Jun Sung Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Ji Hoon Shim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Hongki Min
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Eunjip Choi
- Physics Department, University of Seoul, Seoul 02504, Korea
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45
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Nakamura T, Sugihara H, Chen Y, Yukawa R, Ohtsubo Y, Tanaka K, Kitamura M, Kumigashira H, Kimura SI. Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu 2. Nat Commun 2023; 14:7850. [PMID: 38040781 PMCID: PMC10692116 DOI: 10.1038/s41467-023-43662-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 11/16/2023] [Indexed: 12/03/2023] Open
Abstract
The Kondo effect between localized f-electrons and conductive carriers leads to exotic physical phenomena. Among them, heavy-fermion (HF) systems, in which massive effective carriers appear due to the Kondo effect, have fascinated many researchers. Dimensionality is also an important characteristic of the HF system, especially because it is strongly related to quantum criticality. However, the realization of the perfect two-dimensional (2D) HF materials is still a challenging topic. Here, we report the surface electronic structure of the monoatomic-layer Kondo lattice YbCu2 on a Cu(111) surface observed by synchrotron-based angle-resolved photoemission spectroscopy. The 2D conducting band and the Yb 4f state, located very close to the Fermi level, are observed. These bands are hybridized at low-temperature, forming the 2D HF state, with an evaluated coherence temperature of about 30 K. The effective mass of the 2D state is enhanced by a factor of 100 by the development of the HF state. Furthermore, clear evidence of the hybridization gap formation in the temperature dependence of the Kondo-resonance peak has been observed below the coherence temperature. Our study provides a new candidate as an ideal 2D HF material for understanding the Kondo effect at low dimensions.
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Affiliation(s)
- Takuto Nakamura
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan.
| | - Hiroki Sugihara
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan
| | - Yitong Chen
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan
| | - Ryu Yukawa
- Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan
| | - Yoshiyuki Ohtsubo
- National Institutes for Quantum Science and Technology, Sendai, 980-8579, Japan
| | | | - Miho Kitamura
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan
| | - Hiroshi Kumigashira
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, 980-8577, Japan
| | - Shin-Ichi Kimura
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan.
- Institute for Molecular Science, Okazaki, 444-8585, Japan.
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46
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Sanchez JJ, Fabbris G, Choi Y, DeStefano JM, Rosenberg E, Shi Y, Malinowski P, Huang Y, Mazin II, Kim JW, Chu JH, Ryan PJ. Strain-switchable field-induced superconductivity. SCIENCE ADVANCES 2023; 9:eadj5200. [PMID: 38000034 PMCID: PMC10672156 DOI: 10.1126/sciadv.adj5200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/26/2023] [Indexed: 11/26/2023]
Abstract
Field-induced superconductivity is a rare phenomenon where an applied magnetic field enhances or induces superconductivity. Here, we use applied stress as a control switch between a field-tunable superconducting state and a robust non-field-tunable state. This marks the first demonstration of a strain-tunable superconducting spin valve with infinite magnetoresistance. We combine tunable uniaxial stress and applied magnetic field on the ferromagnetic superconductor Eu(Fe0.88Co0.12)2As2 to shift the field-induced zero-resistance temperature between 4 K and a record-high value of 10 K. We use x-ray diffraction and spectroscopy measurements under stress and field to reveal that strain tuning of the nematic order and field tuning of the ferromagnetism act as independent control parameters of the superconductivity. Combining comprehensive measurements with DFT calculations, we propose that field-induced superconductivity arises from a novel mechanism, namely, the uniquely dominant effect of the Eu dipolar field when the exchange field splitting is nearly zero.
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Affiliation(s)
- Joshua J. Sanchez
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Gilberto Fabbris
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | | | - Elliott Rosenberg
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Yue Shi
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Paul Malinowski
- Department of Physics, University of Washington, Seattle, WA 98195, USA
- Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Yina Huang
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou 310023, People’s Republic of China
| | - Igor I. Mazin
- Department of Physics and Astronomy and Quantum Science and Engineering Center, George Mason University, Fairfax, VA 22030, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Philip J. Ryan
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
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47
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Bairwa JK, Rani M, Kamlesh PK, Singh R, Rani U, Al-Qaisi S, Kumar T, Kumari S, Verma AS. Modeling and simulation of multifaceted properties of X 2NaIO 6 (X = Ca and Sr) double perovskite oxides for advanced technological applications. J Mol Model 2023; 29:379. [PMID: 37978086 DOI: 10.1007/s00894-023-05786-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
CONTEXT In this study, the authors have investigated the structural, optoelectronic, thermoelectric, and thermodynamic properties of Ca2NaIO6 and Sr2NaIO6 double perovskite oxides. Both materials exhibit semiconductor behavior with direct band gaps (Eg) of 0.353 eV and 0.263 eV, respectively. Optical parameters like absorption coefficient α(ω), reflectivity R(ω), dielectric constants, and refractive index have been calculated. The most notable absorption peaks are identified at 5.52 eV (equal to 108.33 × 104 cm-1) in the case of Ca2NaIO6 and at 11.16 eV (equivalent to 118.17 × 104 cm-1) for Sr2NaIO6. These findings suggest a promising outlook for applications in optoelectronics. Moreover, their commendably low thermal conductivity and a high figure of merit, particularly at low temperatures (100 K), indicate their effectiveness as thermoelectric materials. This analysis underscores that these materials hold potential as suitable candidates for n-type doping, making them well-suited for use in thermoelectric devices. Studying thermal properties, including thermal expansion, bulk modulus, acoustic Debye temperature, entropy, and heat capacity, contributes to understanding the materials' thermodynamic stability. The titled materials are dynamically stable. The analysis of these double perovskite materials highlights their potential across various technological applications due to their advantageous structural, electronic, optical, and transport properties, offering new possibilities in material science and technology development. METHODS The study utilized the full potential linearized augmented plane wave (FP-LAPW) method in conjunction with density functional theory within the WIEN2k simulation code. This approach is widely recognized as one of the most dependable methods for evaluating the photovoltaic characteristics of semiconducting perovskites. The thermoelectric properties were ascertained using the rigid band approach and the constant scattering time approximation, both implemented in the BoltzTraP computational code.
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Affiliation(s)
| | - Monika Rani
- Department of Physics, Mohanlal Sukhadia University, Udaipur, Rajasthan, 313001, India
| | - Peeyush Kumar Kamlesh
- School of Basic and Applied Sciences, Nirwan University Jaipur, Jaipur, Rajasthan, 303305, India
| | - Rashmi Singh
- Department of Physics, Institute of Applied Sciences & Humanities, G. L. A. University, Mathura, 281406, India
| | - Upasana Rani
- Division of Research & Innovation, School of Applied and Life Sciences, Uttaranchal University, Dehradun, Uttarakhand, 248007, India
| | - Samah Al-Qaisi
- Palestinian Ministry of Education and Higher Education, Nablus, Palestine
| | - Tanuj Kumar
- Department of Nanoscience and Materials, Central University of Jammu, Jammu, 181143, India
| | - Sarita Kumari
- Department of Physics, University of Rajasthan, Jaipur, Rajasthan, 302004, India
| | - Ajay Singh Verma
- Division of Research & Innovation, School of Applied and Life Sciences, Uttaranchal University, Dehradun, Uttarakhand, 248007, India.
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48
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Kim SW, Conway LJ, Pickard CJ, Pascut GL, Monserrat B. Microscopic theory of colour in lutetium hydride. Nat Commun 2023; 14:7360. [PMID: 37963870 PMCID: PMC10646004 DOI: 10.1038/s41467-023-42983-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/25/2023] [Indexed: 11/16/2023] Open
Abstract
Nitrogen-doped lutetium hydride has recently been proposed as a near-ambient-conditions superconductor. Interestingly, the sample transforms from blue to pink to red as a function of pressure, but only the pink phase is claimed to be superconducting. Subsequent experimental studies have failed to reproduce the superconductivity, but have observed pressure-driven colour changes including blue, pink, red, violet, and orange. However, discrepancies exist among these experiments regarding the sequence and pressure at which these colour changes occur. Given the claimed relationship between colour and superconductivity, understanding colour changes in nitrogen-doped lutetium hydride may hold the key to clarifying the possible superconductivity in this compound. Here, we present a full microscopic theory of colour in lutetium hydride, revealing that hydrogen-deficient LuH2 is the only phase which exhibits colour changes under pressure consistent with experimental reports, with a sequence blue-violet-pink-red-orange. The concentration of hydrogen vacancies controls the precise sequence and pressure of colour changes, rationalising seemingly contradictory experiments. Nitrogen doping also modifies the colour of LuH2 but it plays a secondary role compared to hydrogen vacancies. Therefore, we propose hydrogen-deficient LuH2 as the key phase for exploring the superconductivity claim in the lutetium-hydrogen system. Finally, we find no phonon-mediated superconductivity near room temperature in the pink phase.
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Affiliation(s)
- Sun-Woo Kim
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
| | - Lewis J Conway
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
| | - Chris J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
| | - G Lucian Pascut
- MANSiD Research Center and Faculty of Forestry, Stefan Cel Mare University (USV), Suceava, 720229, Romania
| | - Bartomeu Monserrat
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, UK.
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Kang X, Ishikawa R, Belik AA, Tsujimoto Y, Arai M, Kawata S, Yamaura K. Cd 2FeReO 6: A High- TC Double Perovskite Oxide with Remarkable Tunneling Magnetoresistance. Inorg Chem 2023; 62:18474-18484. [PMID: 37905815 DOI: 10.1021/acs.inorgchem.3c02671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
In this study, we successfully synthesized the double perovskite oxide Cd2FeReO6 by using a high-temperature and high-pressure method. The crystal structure was confirmed to belong to the P21/n space group, exhibiting approximately 68% ordering of Fe3+ and Re5+ ions at the perovskite B-site with the remaining regions showing antisite disorder. The measured Curie temperature of Cd2FeReO6 was 460 K, slightly lower than expected but still significantly above room temperature. Remarkably, Cd2FeReO6 displayed a remarkable low-field butterfly type tunneling magnetoresistance of -23% (-37% between the lowest and the largest values) at 5 K and 90 kOe, the highest among the A2FeReO6 (A = Ca, Sr, Pb, Ba) family. First-principles calculations provided insight into the origin of this observed magnetoresistance behavior, revealing Cd2FeReO6's half-metallic ferrimagnetic nature. This research extends our understanding of the double perovskite family and emphasizes its potential significance in the domains of spintronics and materials science. The exploration of differing magnetoresistance behaviors between Cd2FeReO6 and Ca2FeReO6, along with the influence of antisite disorder in Cd2FeReO6, opens intriguing avenues for further research.
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Affiliation(s)
- Xun Kang
- Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Ryuta Ishikawa
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
| | - Alexei A Belik
- Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yoshihiro Tsujimoto
- Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Masao Arai
- Center for Basic Research on Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Satoshi Kawata
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
| | - Kazunari Yamaura
- Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
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50
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Mi W, Luo K, Trickey SB, Pavanello M. Orbital-Free Density Functional Theory: An Attractive Electronic Structure Method for Large-Scale First-Principles Simulations. Chem Rev 2023; 123:12039-12104. [PMID: 37870767 DOI: 10.1021/acs.chemrev.2c00758] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Kohn-Sham Density Functional Theory (KSDFT) is the most widely used electronic structure method in chemistry, physics, and materials science, with thousands of calculations cited annually. This ubiquity is rooted in the favorable accuracy vs cost balance of KSDFT. Nonetheless, the ambitions and expectations of researchers for use of KSDFT in predictive simulations of large, complicated molecular systems are confronted with an intrinsic computational cost-scaling challenge. Particularly evident in the context of first-principles molecular dynamics, the challenge is the high cost-scaling associated with the computation of the Kohn-Sham orbitals. Orbital-free DFT (OFDFT), as the name suggests, circumvents entirely the explicit use of those orbitals. Without them, the structural and algorithmic complexity of KSDFT simplifies dramatically and near-linear scaling with system size irrespective of system state is achievable. Thus, much larger system sizes and longer simulation time scales (compared to conventional KSDFT) become accessible; hence, new chemical phenomena and new materials can be explored. In this review, we introduce the historical contexts of OFDFT, its theoretical basis, and the challenge of realizing its promise via approximate kinetic energy density functionals (KEDFs). We review recent progress on that challenge for an array of KEDFs, such as one-point, two-point, and machine-learnt, as well as some less explored forms. We emphasize use of exact constraints and the inevitability of design choices. Then, we survey the associated numerical techniques and implemented algorithms specific to OFDFT. We conclude with an illustrative sample of applications to showcase the power of OFDFT in materials science, chemistry, and physics.
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Affiliation(s)
- Wenhui Mi
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, PR China
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, PR China
- International Center of Future Science, Jilin University, Changchun 130012, PR China
| | - Kai Luo
- Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, PR China
| | - S B Trickey
- Quantum Theory Project, Department of Physics and Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Michele Pavanello
- Department of Physics and Department of Chemistry, Rutgers University, Newark, New Jersey 07102, United States
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