1
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Corrias M, Papa L, Sokolović I, Birschitzky V, Gorfer A, Setvin M, Schmid M, Diebold U, Reticcioli M, Franchini C. Automated Real-Space Lattice Extraction for Atomic Force Microscopy Images. Mach Learn : Sci Technol 2023. [DOI: 10.1088/2632-2153/acb5e0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Abstract
Analyzing atomically resolved images is a time-consuming process requiring solid experience and substantial human intervention. In addition, the acquired images contain a large amount of information such as crystal structure, presence and distribution of defects, and formation of domains, which need to be resolved to understand a material's surface structure. Therefore, machine learning techniques have been applied in scanning probe and electron microscopies during the last years, aiming for automatized and efficient image analysis. This work introduces a free and open source tool (AiSurf: Automated Identification of Surface Images) developed to inspect atomically resolved images via Scale-Invariant Feature Transform (SIFT) and Clustering Algorithms (CA). AiSurf extracts primitive lattice vectors, unit cells, and structural distortions from the original image, with no pre-assumption on the lattice and minimal user intervention. The method is applied to various atomically resolved non-contact atomic force microscopy (AFM) images of selected surfaces with different levels of complexity: anatase TiO2(101), oxygen deficient rutile TiO2(110) with and without CO adsorbates, SrTiO3(001) with Sr vacancies and graphene with C vacancies. The code delivers excellent results and is tested against atom misclassification and artifacts, thereby facilitating the interpretation of scanning probe microscopy images.
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2
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Wang Z, Reticcioli M, Jakub Z, Sokolović I, Meier M, Boatner LA, Schmid M, Parkinson GS, Diebold U, Franchini C, Setvin M. Surface chemistry on a polarizable surface: Coupling of CO with KTaO 3(001). Sci Adv 2022; 8:eabq1433. [PMID: 35984882 PMCID: PMC9390988 DOI: 10.1126/sciadv.abq1433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Polarizable materials attract attention in catalysis because they have a free parameter for tuning chemical reactivity. Their surfaces entangle the dielectric polarization with surface polarity, excess charge, and orbital hybridization. How this affects individual adsorbed molecules is shown for the incipient ferroelectric perovskite KTaO3. This intrinsically polar material cleaves along (001) into KO- and TaO2-terminated surface domains. At TaO2 terraces, the polarity-compensating excess electrons form a two-dimensional electron gas and can also localize by coupling to ferroelectric distortions. TaO2 terraces host two distinct types of CO molecules, adsorbed at equivalent lattice sites but charged differently as seen in atomic force microscopy/scanning tunneling microscopy. Temperature-programmed desorption shows substantially stronger binding of the charged CO; in density functional theory calculations, the excess charge favors a bipolaronic configuration coupled to the CO. These results pinpoint how adsorption states couple to ferroelectric polarization.
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Affiliation(s)
- Zhichang Wang
- Institute of Applied Physics, TU Wien, Vienna, Austria
- State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Michele Reticcioli
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna, Austria
| | - Zdenek Jakub
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | | | | | - Lynn A. Boatner
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | | | | | - Cesare Franchini
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna, Austria
- Dipartimento di Fisica e Astronomia, Universita di Bologna, 40127 Bologna, Italy
| | - Martin Setvin
- Institute of Applied Physics, TU Wien, Vienna, Austria
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague 8, Czech Republic
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3
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Reticcioli M, Wang Z, Schmid M, Wrana D, Boatner LA, Diebold U, Setvin M, Franchini C. Competing electronic states emerging on polar surfaces. Nat Commun 2022; 13:4311. [PMID: 35879300 PMCID: PMC9314351 DOI: 10.1038/s41467-022-31953-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 07/07/2022] [Indexed: 11/28/2022] Open
Abstract
Excess charge on polar surfaces of ionic compounds is commonly described by the two-dimensional electron gas (2DEG) model, a homogeneous distribution of charge, spatially-confined in a few atomic layers. Here, by combining scanning probe microscopy with density functional theory calculations, we show that excess charge on the polar TaO2 termination of KTaO3(001) forms more complex electronic states with different degrees of spatial and electronic localization: charge density waves (CDW) coexist with strongly-localized electron polarons and bipolarons. These surface electronic reconstructions, originating from the combined action of electron-lattice interaction and electronic correlation, are energetically more favorable than the 2DEG solution. They exhibit distinct spectroscopy signals and impact on the surface properties, as manifested by a local suppression of ferroelectric distortions. Defect-free surfaces with excess charge are typically described as a homogeneous 2D electron gas. Here, in contrast, the authors find that the KTaO3(001) surface hosts a charge density wave coexisting with a pattern of electron polarons, highly localized states of excess electrons bound to a lattice distortion.
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Affiliation(s)
- Michele Reticcioli
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria.,Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Zhichang Wang
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria.,State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Michael Schmid
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Dominik Wrana
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00, Prague 8, Czech Republic
| | - Lynn A Boatner
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Ulrike Diebold
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Martin Setvin
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria. .,Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00, Prague 8, Czech Republic.
| | - Cesare Franchini
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria. .,Dipartimento di Fisica e Astronomia, Università di Bologna, 40127, Bologna, Italy.
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4
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Sombut P, Puntscher L, Atzmueller M, Jakub Z, Reticcioli M, Meier M, Parkinson GS, Franchini C. Role of Polarons in Single-Atom Catalysts: Case Study of Me 1 [Au 1, Pt 1, and Rh 1] on TiO 2(110). Top Catal 2022; 65:1620-1630. [PMID: 36405974 PMCID: PMC9668789 DOI: 10.1007/s11244-022-01651-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2022] [Indexed: 11/29/2022]
Abstract
The local environment of metal-oxide supported single-atom catalysts plays a decisive role in the surface reactivity and related catalytic properties. The study of such systems is complicated by the presence of point defects on the surface, which are often associated with the localization of excess charge in the form of polarons. This can affect the stability, the electronic configuration, and the local geometry of the adsorbed adatoms. In this work, through the use of density functional theory and surface-sensitive experiments, we study the adsorption of Rh1, Pt1, and Au1 metals on the reduced TiO2(110) surface, a prototypical polaronic material. A systematic analysis of the adsorption configurations and oxidation states of the adsorbed metals reveals different types of couplings between adsorbates and polarons. As confirmed by scanning tunneling microscopy measurements, the favored Pt1 and Au1 adsorption at oxygen vacancy sites is associated with a strong electronic charge transfer from polaronic states to adatom orbitals, which results in a reduction of the adsorbed metal. In contrast, the Rh1 adatoms interact weakly with the excess charge, which leaves the polarons largely unaffected. Our results show that an accurate understanding of the properties of single-atom catalysts on oxide surfaces requires a careful account of the interplay between adatoms, vacancy sites, and polarons. Supplementary Information The online version contains supplementary material available at 10.1007/s11244-022-01651-0.
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Affiliation(s)
| | - Lena Puntscher
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | - Zdenek Jakub
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Michele Reticcioli
- Faculty of Physics, Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
| | - Matthias Meier
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
- Faculty of Physics, Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
| | | | - Cesare Franchini
- Faculty of Physics, Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
- Alma Mater Studiorum, Università di Bologna, 40127 Bologna, Italy
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5
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Garmroudi F, Parzer M, Riss A, Ruban AV, Khmelevskyi S, Reticcioli M, Knopf M, Michor H, Pustogow A, Mori T, Bauer E. Anderson transition in stoichiometric Fe 2VAl: high thermoelectric performance from impurity bands. Nat Commun 2022; 13:3599. [PMID: 35739099 PMCID: PMC9226177 DOI: 10.1038/s41467-022-31159-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/07/2022] [Indexed: 11/22/2022] Open
Abstract
Discovered more than 200 years ago in 1821, thermoelectricity is nowadays of global interest as it enables direct interconversion of thermal and electrical energy via the Seebeck/Peltier effect. In their seminal work, Mahan and Sofo mathematically derived the conditions for ’the best thermoelectric’—a delta-distribution-shaped electronic transport function, where charge carriers contribute to transport only in an infinitely narrow energy interval. So far, however, only approximations to this concept were expected to exist in nature. Here, we propose the Anderson transition in a narrow impurity band as a physical realisation of this seemingly unrealisable scenario. An innovative approach of continuous disorder tuning allows us to drive the Anderson transition within a single sample: variable amounts of antisite defects are introduced in a controlled fashion by thermal quenching from high temperatures. Consequently, we obtain a significant enhancement and dramatic change of the thermoelectric properties from p-type to n-type in stoichiometric Fe2VAl, which we assign to a narrow region of delocalised electrons in the energy spectrum near the Fermi energy. Based on our electronic transport and magnetisation experiments, supported by Monte-Carlo and density functional theory calculations, we present a novel strategy to enhance the performance of thermoelectric materials. The mathematical conditions for the best thermoelectric is well known but never realised in real materials. Here, the authors propose the Anderson transition in a narrow impurity band as a physical realisation of this seemingly unrealisable scenario.
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Affiliation(s)
| | - Michael Parzer
- Institute of Solid State Physics, TU Wien, Vienna, Austria
| | - Alexander Riss
- Institute of Solid State Physics, TU Wien, Vienna, Austria
| | - Andrei V Ruban
- Department of Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.,Materials Center Leoben Forschung GmbH, Leoben, Austria
| | - Sergii Khmelevskyi
- Center for Computational Materials Science and Engineering, TU Wien, Vienna, Austria.
| | - Michele Reticcioli
- Faculty of Physics, Center for Computational Materials Science, Universität Wien, Vienna, Austria
| | - Matthias Knopf
- Institute of Solid State Physics, TU Wien, Vienna, Austria
| | - Herwig Michor
- Institute of Solid State Physics, TU Wien, Vienna, Austria
| | | | - Takao Mori
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Japan.,Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ernst Bauer
- Institute of Solid State Physics, TU Wien, Vienna, Austria
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6
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Reticcioli M, Diebold U, Franchini C. Modeling polarons in density functional theory: lessons learned from TiO 2. J Phys Condens Matter 2022; 34:204006. [PMID: 35213845 DOI: 10.1088/1361-648x/ac58d7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Density functional theory (DFT) is nowadays one of the most broadly used and successful techniques to study the properties of polarons and their effects in materials. Here, we systematically analyze the aspects of the theoretical calculations that are crucial to obtain reliable predictions in agreement with the experimental observations. We focus on rutile TiO2, a prototypical polaronic compound, and compare the formation of polarons on the (110) surface and subsurface atomic layers. As expected, the parameterUused to correct the electronic correlation in the DFT +Uformalism affects the resulting charge localization, local structural distortions and electronic properties of polarons. Moreover, the polaron localization can be driven to different sites by strain: due to different local environments, surface and subsurface polarons show different responses to the applied strain, with impact on the relative energy stability. An accurate description of the properties of polarons is key to understand their impact on complex phenomena and applications: as an example, we show the effects of lattice strain on the interaction between polarons and CO adsorbates.
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Affiliation(s)
- Michele Reticcioli
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Cesare Franchini
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
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7
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Dirnberger D, Kresse G, Franchini C, Reticcioli M. Electronic State Unfolding for Plane Waves: Energy Bands, Fermi Surfaces, and Spectral Functions. J Phys Chem C Nanomater Interfaces 2021; 125:12921-12928. [PMID: 34276866 PMCID: PMC8282185 DOI: 10.1021/acs.jpcc.1c02318] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/26/2021] [Indexed: 05/22/2023]
Abstract
Present day computing facilities allow for first-principles density functional theory studies of complex physical and chemical phenomena. Often such calculations are linked to large supercells to adequately model the desired property. However, supercells are associated with small Brillouin zones in the reciprocal space, leading to folded electronic eigenstates that make the analysis and interpretation extremely challenging. Various techniques have been proposed and developed to reconstruct the electronic band structures of super cells unfolded into the reciprocal space of an ideal primitive cell. Here we propose an unfolding scheme embedded directly in the Vienna Ab initio Simulation Package (VASP) that requires modest computational resources and allows for an automatized mapping from the reciprocal space of the supercell to the primitive cell Brillouin zone. This algorithm can compute band structures, Fermi surfaces, and spectral functions by using an integrated postprocessing tool (bands4vasp). Here the method is applied to a selected variety of complex physical situations: the effect of doping on the band dispersion in the BaFe2(1-x)Ru2x As2 superconductor, the interaction between adsorbates and polaronic states on the TiO2(110) surface, and the band splitting induced by noncollinear spin fluctuations in EuCd2As2.
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Affiliation(s)
- David Dirnberger
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
| | - Georg Kresse
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
- VASP
Software GmbH, 1090 Vienna, Austria
| | - Cesare Franchini
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
- Dipartimento
di Fisica e Astronomia, Università
di Bologna, 40127 Bologna, Italy
| | - Michele Reticcioli
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
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8
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Sokolović I, Reticcioli M, Čalkovský M, Wagner M, Schmid M, Franchini C, Diebold U, Setvín M. Resolving the adsorption of molecular O 2 on the rutile TiO 2(110) surface by noncontact atomic force microscopy. Proc Natl Acad Sci U S A 2020; 117:14827-14837. [PMID: 32527857 PMCID: PMC7334520 DOI: 10.1073/pnas.1922452117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interaction of molecular oxygen with semiconducting oxide surfaces plays a key role in many technologies. The topic is difficult to approach both by experiment and in theory, mainly due to multiple stable charge states, adsorption configurations, and reaction channels of adsorbed oxygen species. Here we use a combination of noncontact atomic force microscopy (AFM) and density functional theory (DFT) to resolve [Formula: see text] adsorption on the rutile [Formula: see text](110) surface, which presents a longstanding challenge in the surface chemistry of metal oxides. We show that chemically inert AFM tips terminated by an oxygen adatom provide excellent resolution of both the adsorbed species and the oxygen sublattice of the substrate. Adsorbed [Formula: see text] molecules can accept either one or two electron polarons from the surface, forming superoxo or peroxo species. The peroxo state is energetically preferred under any conditions relevant for applications. The possibility of nonintrusive imaging allows us to explain behavior related to electron/hole injection from the tip, interaction with UV light, and the effect of thermal annealing.
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Affiliation(s)
- Igor Sokolović
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
| | - Michele Reticcioli
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
- Faculty of Physics, University of Vienna, 1090 Vienna, Austria
- Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
| | - Martin Čalkovský
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
- Institute of Physical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic
| | - Margareta Wagner
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
- Central European Institute of Technology, Brno University of Technology, 612 00 Brno, Czech Republic
| | - Michael Schmid
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
| | - Cesare Franchini
- Faculty of Physics, University of Vienna, 1090 Vienna, Austria
- Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
| | - Ulrike Diebold
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria
| | - Martin Setvín
- Institute of Applied Physics, Technische Universität Wien, 1040 Vienna, Austria;
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague 8, Czech Republic
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9
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Ma JZ, Nie SM, Yi CJ, Jandke J, Shang T, Yao MY, Naamneh M, Yan LQ, Sun Y, Chikina A, Strocov VN, Medarde M, Song M, Xiong YM, Xu G, Wulfhekel W, Mesot J, Reticcioli M, Franchini C, Mudry C, Müller M, Shi YG, Qian T, Ding H, Shi M. Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd 2As 2. Sci Adv 2019; 5:eaaw4718. [PMID: 31309151 PMCID: PMC6625818 DOI: 10.1126/sciadv.aaw4718] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 06/10/2019] [Indexed: 05/22/2023]
Abstract
Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi-long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.
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Affiliation(s)
- J.-Z. Ma
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15 Lausanne, Switzerland
| | - S. M. Nie
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - C. J. Yi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100190, China
| | - J. Jandke
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - T. Shang
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15 Lausanne, Switzerland
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M. Y. Yao
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M. Naamneh
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - L. Q. Yan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Y. Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - A. Chikina
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - V. N. Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M. Medarde
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M. Song
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Y.-M. Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - G. Xu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - W. Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - J. Mesot
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M. Reticcioli
- Faculty of Physics, Center for Computational Materials Science, University of Vienna, A-1090 Vienna, Austria
| | - C. Franchini
- Faculty of Physics, Center for Computational Materials Science, University of Vienna, A-1090 Vienna, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
| | - C. Mudry
- Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, Ecole Polytechnique Federale de Lausanne, CH1015 Lausanne, Switzerland
| | - M. Müller
- Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Y. G. Shi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - T. Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - H. Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - M. Shi
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
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10
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Dobrovits S, Kim B, Reticcioli M, Toschi A, Khmelevskyi S, Franchini C. Doping-induced insulator-metal transition in the Lifshitz magnetic insulator NaOsO 3. J Phys Condens Matter 2019; 31:244002. [PMID: 30844783 DOI: 10.1088/1361-648x/ab0dc4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
By means of first principles schemes based on magnetically constrained density functional theory and on the band unfolding technique we study the effect of doping on the conducting behaviour of the Lifshitz magnetic insulator NaOsO3. Electron doping is treated within a supercell approach by replacing sodium with magnesium at different concentrations ([Formula: see text], [Formula: see text]). Undoped NaOsO3 is subjected to a temperature-driven Lifshitz transition involving a continuous closing of the gap due to longitudinal and rotational spin fluctuations (Kim et al 2016 Phys. Rev. B 94 241113). Here we find that Mg doping suppresses the insulating state, gradually drives the system to a metallic state (via an intermediate bad metal phase) and the transition is accompanied by a progressive lowering of the Os magnetic moment. We inspected the role of longitudinal spin fluctuations by constraining the amplitude of the local Os moments and found that a robust metal state can be achieved below a critical moment. In analogy with the undoped case we conjecture that the decrease of the local moment can be controlled by temperature effects, in accordance with the theory of itinerant electron magnetism.
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Affiliation(s)
- Sabine Dobrovits
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Sensengasse 8, A-1090 Vienna, Austria
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11
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Reticcioli M, Sokolović I, Schmid M, Diebold U, Setvin M, Franchini C. Interplay between Adsorbates and Polarons: CO on Rutile TiO_{2}(110). Phys Rev Lett 2019; 122:016805. [PMID: 31012645 DOI: 10.1103/physrevlett.122.016805] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 11/26/2018] [Indexed: 06/09/2023]
Abstract
Polaron formation plays a major role in determining the structural, electrical, and chemical properties of ionic crystals. Using a combination of first-principles calculations, scanning tunneling microscopy, and atomic force microscopy, we analyze the interaction of polarons with CO molecules adsorbed on the reduced rutile TiO_{2}(110) surface. Adsorbed CO shows attractive coupling with polarons in the surface layer, and repulsive interaction with polarons in the subsurface layer. As a result, CO adsorption depends on the reduction state of the sample. For slightly reduced surfaces, many adsorption configurations with comparable adsorption energies exist and polarons reside in the subsurface layer. At strongly reduced surfaces, two adsorption configurations dominate: either inside an oxygen vacancy, or at surface Ti_{5c} sites, coupled with a surface polaron. Similar conclusions are predicted for TiO_{2}(110) surfaces containing near-surface Ti interstitials. These results show that polarons are of primary importance for understanding the performance of polar semiconductors and transition metal oxides in catalysis and energy-related applications.
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Affiliation(s)
- Michele Reticcioli
- University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna 1090, Austria
| | - Igor Sokolović
- Institute of Applied Physics, Technische Universität Wien, Vienna 1090, Austria
| | - Michael Schmid
- Institute of Applied Physics, Technische Universität Wien, Vienna 1090, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, Technische Universität Wien, Vienna 1090, Austria
| | - Martin Setvin
- Institute of Applied Physics, Technische Universität Wien, Vienna 1090, Austria
| | - Cesare Franchini
- University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna 1090, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
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Setvin M, Reticcioli M, Poelzleitner F, Hulva J, Schmid M, Boatner LA, Franchini C, Diebold U. Polarity compensation mechanisms on the perovskite surface KTaO
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(001). Science 2018; 359:572-575. [DOI: 10.1126/science.aar2287] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/19/2017] [Indexed: 11/02/2022]
Affiliation(s)
- Martin Setvin
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Michele Reticcioli
- University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna, Austria
| | - Flora Poelzleitner
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Jan Hulva
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Michael Schmid
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
| | - Lynn A. Boatner
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Cesare Franchini
- University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, Technische Universität Wien, Vienna, Austria
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