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Zhang F, Liu H, Tao F, Wang X, Cao X, Hu W. Tunable Electric and Magnetic Properties of Transition Metal@N x C y -Graphene Materials by Different Metal and Defect Types. Chem Asian J 2021; 16:3230-3235. [PMID: 34411460 DOI: 10.1002/asia.202100752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/17/2021] [Indexed: 11/09/2022]
Abstract
Transition metal@Nx Cy -graphene (TM@Nx Cy -GR) materials have been widely used as redox reaction catalysts in the field of fuel cells due to their low cost and high performance. In the present work, we systematically investigate the effect of different metal and defect types on the electro-magnetic properties of TM@Nx Cy -GR materials using first principles calculations. Our simulations show that TM@N3 -GR (the minimum defect size) and TM@N7 -GR (the maximum defect size) materials always possess metallic property regardless the metal type. However, doping different TM can regulate the medium defects (TM@N2 C2 -GR-I and TM@N2 C2 -GR-II) among metallicity, half-metallicity and semi-conductivity. In addition, we found that different TM and defect type largely affects the magnetic moment. The spin density and projected density of state calculations show that the net charges of the defect structure are mainly located near the hole, and the magnetic regulation comes from the coupling of TM-d orbital with carbon (nitrogen)-s(p) orbitals. The present study provides abundant valuable information for the TM@Nx Cy -GR materials designs and applicants in the future.
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Affiliation(s)
- Fengxiang Zhang
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Chemical Engineering, Qilu University of Technology, Jinan, Shandong, 250353, P. R. China
| | - Haixia Liu
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Chemical Engineering, Qilu University of Technology, Jinan, Shandong, 250353, P. R. China
| | - Furong Tao
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Chemical Engineering, Qilu University of Technology, Jinan, Shandong, 250353, P. R. China
| | - Xijun Wang
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, 27606, USA
| | - Xinrui Cao
- Department of Physics and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen University, Xiamen, Fujian, 361005, P. R. China
| | - Wei Hu
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Chemical Engineering, Qilu University of Technology, Jinan, Shandong, 250353, P. R. China
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Kim H, Rózsa L, Schreyer D, Simon E, Wiesendanger R. Long-range focusing of magnetic bound states in superconducting lanthanum. Nat Commun 2020; 11:4573. [PMID: 32917904 PMCID: PMC7486372 DOI: 10.1038/s41467-020-18406-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 08/21/2020] [Indexed: 11/08/2022] Open
Abstract
Quantum mechanical systems with long-range interactions between quasiparticles provide a promising platform for coherent quantum information technology. Superconductors are a natural choice for solid-state based quantum devices, while magnetic impurities inside superconductors give rise to quasiparticle excitations of broken Cooper pairs that provide characteristic information about the host superconductor. Here, we reveal that magnetic impurities embedded below a superconducting La(0001) surface interact via quasiparticles extending to very large distances, up to several tens of nanometers. Using low-temperature scanning probe techniques, we observe the corresponding anisotropic and giant oscillations in the LDOS. Theoretical calculations indicate that the quasi-two-dimensional surface states with their strongly anisotropic Fermi surface play a crucial role for the focusing and long-range extension of the magnetic bound states. The quasiparticle focusing mechanism should facilitate the design of versatile magnetic structures with tunable and directed magnetic interactions over large distances, thereby paving the way toward the design of low-dimensional magnet-superconductor hybrid systems exhibiting topologically non-trivial quantum states as possible elements of quantum computation schemes based on Majorana quasiparticles.
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Affiliation(s)
- Howon Kim
- Department of Physics, University of Hamburg, D-20355, Hamburg, Germany.
| | - Levente Rózsa
- Department of Physics, University of Hamburg, D-20355, Hamburg, Germany
- Department of Physics, University of Konstanz, D-78457, Konstanz, Germany
| | - Dominik Schreyer
- Department of Physics, University of Hamburg, D-20355, Hamburg, Germany
| | - Eszter Simon
- Department of Theoretical Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111, Budapest, Hungary
- Department Chemie, Physikalische Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, D-81377, München, Germany
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3
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Hsieh S, Bhattacharyya P, Zu C, Mittiga T, Smart TJ, Machado F, Kobrin B, Höhn TO, Rui NZ, Kamrani M, Chatterjee S, Choi S, Zaletel M, Struzhkin VV, Moore JE, Levitas VI, Jeanloz R, Yao NY. Imaging stress and magnetism at high pressures using a nanoscale quantum sensor. Science 2019; 366:1349-1354. [DOI: 10.1126/science.aaw4352] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 11/06/2019] [Indexed: 01/19/2023]
Abstract
Pressure alters the physical, chemical, and electronic properties of matter. The diamond anvil cell enables tabletop experiments to investigate a diverse landscape of high-pressure phenomena. Here, we introduce and use a nanoscale sensing platform that integrates nitrogen-vacancy (NV) color centers directly into the culet of diamond anvils. We demonstrate the versatility of this platform by performing diffraction-limited imaging of both stress fields and magnetism as a function of pressure and temperature. We quantify all normal and shear stress components and demonstrate vector magnetic field imaging, enabling measurement of the pressure-driven α↔ϵ phase transition in iron and the complex pressure-temperature phase diagram of gadolinium. A complementary NV-sensing modality using noise spectroscopy enables the characterization of phase transitions even in the absence of static magnetic signatures.
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Affiliation(s)
- S. Hsieh
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - P. Bhattacharyya
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - C. Zu
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - T. Mittiga
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - T. J. Smart
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| | - F. Machado
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - B. Kobrin
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - T. O. Höhn
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Fakultät für Physik, Ludwig-Maximilians-Universität München, 80799 Munich, Germany
| | - N. Z. Rui
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - M. Kamrani
- Department of Aerospace Engineering, Iowa State University, Ames, IA 50011, USA
| | - S. Chatterjee
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - S. Choi
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - M. Zaletel
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - V. V. Struzhkin
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - J. E. Moore
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - V. I. Levitas
- Department of Aerospace Engineering, Iowa State University, Ames, IA 50011, USA
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
- Ames Laboratory, Division of Materials Science and Engineering, Ames, IA 50011, USA
| | - R. Jeanloz
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| | - N. Y. Yao
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Zhang GP, Jenkins T, Bennett M, Bai YH. Manifestation of intra-atomic 5d6s-4f exchange coupling in photoexcited gadolinium. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:495807. [PMID: 29105644 DOI: 10.1088/1361-648x/aa986c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Intra-atomic exchange couplings (IECs) between 5d6s and 4f electrons are ubiquitous in rare-earth metals and play a critical role in spin dynamics. However, detecting them in real time domain has been difficult. Here we show the direct evidence of IEC between 5d6s and 4f electrons in gadolinium. Upon femtosecond laser excitation, 5d6s electrons are directly excited; their majority bands shift toward the Fermi level while their minority bands do the opposite. For the first time, our first-principles minority shift now agrees with the experiment quantitatively. Excited 5d6s electrons lower the exchange potential barrier for 4f electrons, so the 4f states are also shifted in energy, a prediction that can be tested experimentally. Although a significant number of 5d6s electrons, some several eV below the Fermi level, are excited out of the Fermi sea, there is no change in the 4f states, a clear manifestation of intra-atomic exchange coupling.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
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Mendive-Tapia E, Staunton JB. Theory of Magnetic Ordering in the Heavy Rare Earths: Ab Initio Electronic Origin of Pair- and Four-Spin Interactions. PHYSICAL REVIEW LETTERS 2017; 118:197202. [PMID: 28548504 DOI: 10.1103/physrevlett.118.197202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Indexed: 06/07/2023]
Abstract
We describe a disordered local moment theory for long-period magnetic phases and investigate the temperature and magnetic field dependence of the magnetic states in the heavy rare earth elements (HREs), namely, paramagnetic, conical and helical antiferromagnetic (HAFM), fan, and ferromagnetic (FM) states. We obtain a generic HRE magnetic phase diagram which is consequent on the response of the common HRE valence electronic structure to f-electron magnetic moment ordering. The theory directly links the first-order HAFM-FM transition to the loss of Fermi surface nesting, induced by this magnetic ordering, as well as provides a template for analyzing the other phases and exposing where f-electron correlation effects are particularly intricate. Gadolinium, for a range of hexagonal, close-packed lattice constants c and a, is the prototype, described ab initio, and applications to other HREs are made straightforwardly by scaling the effective pair and quartic local moment interactions that emerge naturally from the theory with de Gennes factors and choosing appropriate lanthanide-contracted c and a values.
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Affiliation(s)
| | - Julie B Staunton
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
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Roth D, Bruckner B, Moro MV, Gruber S, Goebl D, Juaristi JI, Alducin M, Steinberger R, Duchoslav J, Primetzhofer D, Bauer P. Electronic Stopping of Slow Protons in Transition and Rare Earth Metals: Breakdown of the Free Electron Gas Concept. PHYSICAL REVIEW LETTERS 2017; 118:103401. [PMID: 28339263 DOI: 10.1103/physrevlett.118.103401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 06/06/2023]
Abstract
The electronic stopping cross sections (SCS) of Ta and Gd for slow protons have been investigated experimentally. The data are compared to the results for Pt and Au to learn how electronic stopping in transition and rare earth metals correlates with features of the electronic band structures. The extraordinarily high SCS observed for protons in Ta and Gd cannot be understood in terms of a free electron gas model, but are related to the high densities of both occupied and unoccupied electronic states in these metals.
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Affiliation(s)
- D Roth
- Johannes-Kepler Universität Linz, IEP-AOP, Altenbergerstraße 69, A-4040 Linz, Austria
| | - B Bruckner
- Johannes-Kepler Universität Linz, IEP-AOP, Altenbergerstraße 69, A-4040 Linz, Austria
| | - M V Moro
- Johannes-Kepler Universität Linz, IEP-AOP, Altenbergerstraße 69, A-4040 Linz, Austria
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, 05508-090 São Paulo, Brasil
| | - S Gruber
- Johannes-Kepler Universität Linz, IEP-AOP, Altenbergerstraße 69, A-4040 Linz, Austria
| | - D Goebl
- Johannes-Kepler Universität Linz, IEP-AOP, Altenbergerstraße 69, A-4040 Linz, Austria
| | - J I Juaristi
- Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián, Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Departamento de Física de Materiales, Facultad de Químicas, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20018 San Sebastián, Spain
| | - M Alducin
- Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián, Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - R Steinberger
- Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterization, Zentrum für Oberflächen- und Nanoanalytik (ZONA), Johannes-Kepler Universität Linz, Altenbergerstraße 69, A-4040 Linz Austria
| | - J Duchoslav
- Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterization, Zentrum für Oberflächen- und Nanoanalytik (ZONA), Johannes-Kepler Universität Linz, Altenbergerstraße 69, A-4040 Linz Austria
| | - D Primetzhofer
- Institutionen för Fysik och Astronomi, Uppsala Universitet, Box 516, S-751 20 Uppsala, Sweden
| | - P Bauer
- Johannes-Kepler Universität Linz, IEP-AOP, Altenbergerstraße 69, A-4040 Linz, Austria
- Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián, Spain
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Carva K, Baláž P, Radu I. Laser-Induced Ultrafast Magnetic Phenomena. HANDBOOK OF MAGNETIC MATERIALS 2017. [DOI: 10.1016/bs.hmm.2017.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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Magnetic ordering temperature of nanocrystalline Gd: enhancement of magnetic interactions via hydrogenation-induced "negative" pressure. Sci Rep 2016; 6:22553. [PMID: 26931775 PMCID: PMC4773832 DOI: 10.1038/srep22553] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/16/2016] [Indexed: 11/17/2022] Open
Abstract
Gadolinium is a nearly ideal soft-magnetic material. However, one cannot take advantage of its properties at temperatures higher than the room temperature where Gd loses the ferromagnetic ordering. By using high-purity bulk samples with grains ~200 nm in size, we present proof-of-concept measurements of an increased Curie point (TC) and spontaneous magnetization in Gd due to hydrogenation. From first-principles we explain increase of TC in pure Gd due to the addition of hydrogen. We show that the interplay of the characteristic features in the electronic structure of the conduction band at the Fermi level in the high-temperature paramagnetic phase of Gd and “negative” pressure exerted by hydrogen are responsible for the observed effect.
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