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Kang CJ, Kim K, Min BI. Band theoretical approaches to topological physics in strongly-correlated f-electron Kondo systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:271501. [PMID: 35073534 DOI: 10.1088/1361-648x/ac4e47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
First-principles band structure theory on the basis of the density functional theory (DFT) plays an essential role in the investigation of topological properties of weakly-correlated systems. DFT band structures show clear bulk band crossings for Weyl and Dirac semimetals, and surface band crossings for topological insulators and topological-crystalline insulators. In contrast, for strongly-correlatedf-electron systems, their topological properties are relatively less explored because the simple DFT does not work properly in describing the electronic structures of strongly-correlatedfelectrons. In this perspective, we examine the band theoretical approaches to topological properties of strongly-correlatedf-electron Kondo systems. We recapitulate current status of understanding of electronic structures and topological properties of strongly-correlated 4f-electron systems, such as Ce, SmB6, and g-SmS, and also a 5f-electron system PuB4, the electronic structures of which were investigated by the DFT combined with the dynamical mean-field theory (DFT + DMFT). Finally, we provide future directions and perspectives of improving theoretical band approaches to search for new topologicalf-electron systems, as an outlook.
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Affiliation(s)
- Chang-Jong Kang
- Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Kyoo Kim
- Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero, Daejeon 34057, Republic of Korea
| | - B I Min
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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2
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Li Z, Cheng Y, Zheng X, Wei J, Yan Y, Luo HG. Study the mixed valence problem in asymmetric Anderson model: Fano-Kondo resonance around Fermi level. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:255601. [PMID: 35378517 DOI: 10.1088/1361-648x/ac640a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 04/04/2022] [Indexed: 06/14/2023]
Abstract
We numerically calculate the local density of states (LDOS) in asymmetric Anderson model in mixed valence regime using hierarchical equations of motion approach. Based on the idea that the asymmetric line shape of LDOS around Fermi level stems from the interference between the single particle resonance and the Kondo resonance, we perform a fitting. From the fitting results, we obtain the Kondo temperatures and the Fano factors with changing the single particle energy. The tendency of Kondo temperature agrees with the previous analytic expressions and the Fano factors are in an expected variation of Fano resonance. Our study shows that the Fano-Kondo resonance can reasonably explain the asymmetric line shape of the LDOS around the Fermi level.
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Affiliation(s)
- ZhenHua Li
- School of Physical Science and Technology & Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, People's Republic of China
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
| | - YongXi Cheng
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
- Department of Science, Taiyuan Institute of Technology, Taiyuan 030008, People's Republic of China
| | - Xiao Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale & Synergetic Innovation Center of Quantum Information and Quantum Physics & CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - JianHua Wei
- Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China
| | - YiJing Yan
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Hong-Gang Luo
- School of Physical Science and Technology & Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, People's Republic of China
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
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3
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Ryu DC, Kim J, Choi H, Min BI. Wallpaper Dirac Fermion in a Nonsymmorphic Topological Kondo Insulator: PuB 4. J Am Chem Soc 2020; 142:19278-19282. [PMID: 33113332 DOI: 10.1021/jacs.0c09442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It has been recently predicted that nonsymmorphic crystalline insulators can host two exotic topological surface states (TSSs). One is the "hourglass fermion", and the other is the "wallpaper Dirac fermion". For the former, a few real materials were predicted and already confirmed experimentally. For the latter, however, no bulk-insulating and experimentally accessible candidate has been identified yet. Here we show that the localized 5f-electrons in PuB4, the single crystal of which was recently synthesized and was found to exhibit Kondo-insulating nature, form a closed manifold over the Brillouin zone via the Kondo coherence effect at low temperature, and host hitherto unobserved wallpaper Dirac fermions at the nonsymmorphic symmetry-preserving (001) surface. The topological nature of TSSs in PuB4 can be described by topological invariants of two Z4 indices [(χx, χy) = (1, 1)] of double-glide symmetries of p4g wallpaper group; thus, PuB4 is a 3D nonsymmorphic topological insulator that exhibits the TSSs of peculiar 4-fold surface Dirac fermions as well as 2-fold double-glide spin-Hall and nodal-line-type fermions. On top of its interesting 5f-electron Kondo-insulating nature, the unique 4-fold wallpaper Dirac fermions in PuB4, which are quite distinct from previously reported nonsymmorphic Dirac insulator or hourglass TCI fermions, broaden our recognition of the embedded fermions in strongly correlated Kondo systems with nonsymmorphic symmetries.
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Affiliation(s)
- Dong-Choon Ryu
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Junwon Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Hongchul Choi
- IBS Center for Correlated Electron Systems, Seoul National University, Seoul 08826, Korea
| | - Byung Il Min
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
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Mazzone DG, Dzero M, Abeykoon AM, Yamaoka H, Ishii H, Hiraoka N, Rueff JP, Ablett JM, Imura K, Suzuki HS, Hancock JN, Jarrige I. Kondo-Induced Giant Isotropic Negative Thermal Expansion. PHYSICAL REVIEW LETTERS 2020; 124:125701. [PMID: 32281848 DOI: 10.1103/physrevlett.124.125701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 02/14/2020] [Indexed: 06/11/2023]
Abstract
Negative thermal expansion is an unusual phenomenon appearing in only a handful of materials, but pursuit and mastery of the phenomenon holds great promise for applications across disciplines and industries. Here we report use of x-ray spectroscopy and diffraction to investigate the 4f-electronic properties in Y-doped SmS and employ the Kondo volume collapse model to interpret the results. Our measurements reveal an unparalleled decrease of the bulk Sm valence by over 20% at low temperatures in the mixed-valent golden phase, which we show is caused by a strong coupling between an emergent Kondo lattice state and a large isotropic volume change. The amplitude and temperature range of the negative thermal expansion appear strongly dependent on the Y concentration and the associated chemical disorder, providing control over the observed effect. This finding opens avenues for the design of Kondo lattice materials with tunable, giant, and isotropic negative thermal expansion.
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Affiliation(s)
- D G Mazzone
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - M Dzero
- Department of Physics, Kent State University, Kent, Ohio 44242, USA
| | - Am M Abeykoon
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - H Yamaoka
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - H Ishii
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - N Hiraoka
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - J-P Rueff
- Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette, France
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, 75005 Paris, France
| | - J M Ablett
- Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - K Imura
- Department of Physics, Nagoya University, Nagoya 464-8602, Japan
| | - H S Suzuki
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science (NIMS), Sengen, Tsukuba 305-0047, Japan
- The Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa 277-8581, Japan
| | - J N Hancock
- Department of Physics and Institute for Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA
| | - I Jarrige
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
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Sousanis A, Poelman D, Detavernier C, Smet PF. Switchable Piezoresistive SmS Thin Films on Large Area. SENSORS (BASEL, SWITZERLAND) 2019; 19:s19204390. [PMID: 31614444 PMCID: PMC6832629 DOI: 10.3390/s19204390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Samarium monosulfide (SmS) is a switchable material, showing a pressure-induced semiconductor to metal transition. As such, it can be used in different applications such as piezoresistive sensors and memory devices. In this work, we present how e-beam sublimation of samarium metal in a reactive atmosphere can be used for the deposition of semiconducting SmS thin films on 150 mm diameter silicon wafers. The deposition parameters influencing the composition and properties of the thin films are evaluated, such as the deposition rate of Sm metal, the substrate temperature and the H2S partial pressure. We then present the changes in the optical, structural and electrical properties of this compound after the pressure-induced switching to the metallic state. The back-switching and stability of SmS thin films are studied as a function of temperature and atmosphere via in-situ X-ray diffraction. The thermally induced back switching initiates at 250 °C, while above 500 °C, Sm2O2S is formed. Lastly, we explore the possibility to determine the valence state of the samarium ions by means of X-ray photoelectron spectroscopy.
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Affiliation(s)
- Andreas Sousanis
- Lumilab, Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium.
| | - Dirk Poelman
- Lumilab, Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium.
| | - Christophe Detavernier
- Cocoon, Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium.
| | - Philippe F Smet
- Lumilab, Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium.
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6
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Hwang J, Kim K, Ryu H, Kim J, Lee JE, Kim S, Kang M, Park BG, Lanzara A, Chung J, Mo SK, Denlinger J, Min BI, Hwang C. Emergence of Kondo Resonance in Graphene Intercalated with Cerium. NANO LETTERS 2018; 18:3661-3666. [PMID: 29761696 DOI: 10.1021/acs.nanolett.8b00784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body interaction in solid and its relation to magnetism. Kondo effect, the formation of a new resonant ground state with quenched magnetic moment, provides a general framework to describe many-body interaction in the presence of magnetic impurity. In this Letter, a combined study of angle-resolved photoemission (ARPES) and dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi energy, EF, hybridized with the graphene π-band, exhibit gradual increase in spectral weight upon decreasing temperature. The observed temperature dependence follows the expectations from the Kondo picture in the weak coupling limit. Our results provide a novel insight how Kondo physics emerges in the sea of two-dimensional Dirac electrons.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Kyoo Kim
- Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Hyejin Ryu
- Department of Physics , Pusan National University , Busan 46241 , Korea
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Center for Spintronics , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Jingul Kim
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Ji-Eun Lee
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Sooran Kim
- Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials , Pohang University of Science and Technology , Pohang 37673 , Korea
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Minhee Kang
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Byeong-Gyu Park
- Pohang Accelerator Laboratory , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Alessandra Lanzara
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Physics , University of California , Berkeley , California 94720 , United States
| | - Jinwook Chung
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
- Department of Physics and Photon Science , Gwangju Institute of Science and Technology , Gwangju 61005 , Korea
| | - Sung-Kwan Mo
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Jonathan Denlinger
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Byung Il Min
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Choongyu Hwang
- Department of Physics , Pusan National University , Busan 46241 , Korea
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7
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Near-field spectroscopic investigation of dual-band heavy fermion metamaterials. Nat Commun 2017; 8:2262. [PMID: 29273808 PMCID: PMC5741627 DOI: 10.1038/s41467-017-02378-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/22/2017] [Indexed: 11/11/2022] Open
Abstract
Broadband tunability is a central theme in contemporary nanophotonics and metamaterials research. Combining metamaterials with phase change media offers a promising approach to achieve such tunability, which requires a comprehensive investigation of the electromagnetic responses of novel materials at subwavelength scales. In this work, we demonstrate an innovative way to tailor band-selective electromagnetic responses at the surface of a heavy fermion compound, samarium sulfide (SmS). By utilizing the intrinsic, pressure sensitive, and multi-band electron responses of SmS, we create a proof-of-principle heavy fermion metamaterial, which is fabricated and characterized using scanning near-field microscopes with <50 nm spatial resolution. The optical responses at the infrared and visible frequency ranges can be selectively and separately tuned via modifying the occupation of the 4f and 5d band electrons. The unique pressure, doping, and temperature tunability demonstrated represents a paradigm shift for nanoscale metamaterial and metasurface design. Understanding the electromagnetic responses at subwavelength scales is important for achieving tunability. Using a combination of the near-field and far-field spectroscopy, the authors demonstrate a heavy fermion metamaterial with tunable dual-band optical responses by selectively and separately modifying the 4f and 5d band electrons.
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Min CH, Goth F, Lutz P, Bentmann H, Kang BY, Cho BK, Werner J, Chen KS, Assaad F, Reinert F. Matching DMFT calculations with photoemission spectra of heavy fermion insulators: universal properties of the near-gap spectra of SmB 6. Sci Rep 2017; 7:11980. [PMID: 28931836 PMCID: PMC5607333 DOI: 10.1038/s41598-017-12080-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 09/04/2017] [Indexed: 11/11/2022] Open
Abstract
Paramagnetic heavy fermion insulators consist of fully occupied quasiparticle bands inherent to Fermi liquid theory. The gap emergence below a characteristic temperature is the ultimate sign of coherence for a many-body system, which in addition can induce a non-trivial band topology. Here, we demonstrate a simple and efficient method to compare a model study and an experimental result for heavy fermion insulators. The temperature dependence of the gap formation in both local moment and mixed valence regimes is captured within the dynamical mean field (DMFT) approximation to the periodic Anderson model (PAM). Using the topological coherence temperature as the scaling factor and choosing the input parameter set within the mixed valence regime, we can unambiguously link the theoretical energy scales to the experimental ones. As a particularly important result, we find improved consistency between the scaled DMFT density of states and the photoemission near-gap spectra of samarium hexaboride (SmB6).
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Affiliation(s)
- Chul-Hee Min
- Experimentelle Physik VII and Röntgen Research Center for Complex Materials (RCCM), Universität Würzburg, 97074, Würzburg, Germany.
| | - F Goth
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074, Würzburg, Germany
| | - P Lutz
- Experimentelle Physik VII and Röntgen Research Center for Complex Materials (RCCM), Universität Würzburg, 97074, Würzburg, Germany
| | - H Bentmann
- Experimentelle Physik VII and Röntgen Research Center for Complex Materials (RCCM), Universität Würzburg, 97074, Würzburg, Germany
| | - B Y Kang
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - B K Cho
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - J Werner
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074, Würzburg, Germany
| | - K-S Chen
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074, Würzburg, Germany
| | - F Assaad
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074, Würzburg, Germany
| | - F Reinert
- Experimentelle Physik VII and Röntgen Research Center for Complex Materials (RCCM), Universität Würzburg, 97074, Würzburg, Germany
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9
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Samarium Monosulfide (SmS): Reviewing Properties and Applications. MATERIALS 2017; 10:ma10080953. [PMID: 28813006 PMCID: PMC5578319 DOI: 10.3390/ma10080953] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/31/2017] [Accepted: 08/10/2017] [Indexed: 11/17/2022]
Abstract
In this review, we give an overview of the properties and applications of samarium monosulfide, SmS, which has gained considerable interest as a switchable material. It shows a pressure-induced phase transition from the semiconducting to the metallic state by polishing, and it switches back to the semiconducting state by heating. The material also shows a magnetic transition, from the paramagnetic state to an antiferromagnetically ordered state. The switching behavior between the semiconducting and metallic states could be exploited in several applications, such as high density optical storage and memory materials, thermovoltaic devices, infrared sensors and more. We discuss the electronic, optical and magnetic properties of SmS, its switching behavior, as well as the thin film deposition techniques which have been used, such as e-beam evaporation and sputtering. Moreover, applications and possible ideas for future work on this material are presented. Our scope is to present the properties of SmS, which were mainly measured in bulk crystals, while at the same time we describe the possible deposition methods that will push the study of SmS to nanoscale dimensions, opening an intriguing range of applications for low-dimensional, pressure-induced semiconductor-metal transition compounds.
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Petit L, Szotek Z, Lüders M, Svane A. Rare-earth pnictides and chalcogenides from first-principles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:223001. [PMID: 27165563 DOI: 10.1088/0953-8984/28/22/223001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This review tries to establish what is the current understanding of the rare-earth monopnictides and monochalcogenides from first principles. The rock salt structure is assumed for all the compounds in the calculations and wherever possible the electronic structure/properties of these compounds, as obtained from different ab initio methods, are compared and their relation to the experimental evidence is discussed. The established findings are summarised in a set of conclusions and provide outlook for future study and possible design of new materials.
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Affiliation(s)
- L Petit
- Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK
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11
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Kang CJ, Denlinger JD, Allen JW, Min CH, Reinert F, Kang BY, Cho BK, Kang JS, Shim JH, Min BI. Electronic Structure of YbB_{6}: Is it a Topological Insulator or Not? PHYSICAL REVIEW LETTERS 2016; 116:116401. [PMID: 27035312 DOI: 10.1103/physrevlett.116.116401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Indexed: 06/05/2023]
Abstract
To finally resolve the controversial issue of whether or not the electronic structure of YbB_{6} is nontrivially topological, we have made a combined study using angle-resolved photoemission spectroscopy (ARPES) of the nonpolar (110) surface and density functional theory (DFT). The flat-band conditions of the (110) ARPES avoid the strong band bending effects of the polar (001) surface and definitively show that YbB_{6} has a topologically trivial B 2p-Yb 5d semiconductor band gap of ∼0.3 eV. Accurate determination of the low energy band topology in DFT requires the use of a modified Becke-Johnson exchange potential incorporating spin-orbit coupling and an on-site Yb 4f Coulomb interaction U as large as 7 eV. The DFT result, confirmed by a more precise GW band calculation, is similar to that of a small gap non-Kondo nontopological semiconductor. Additionally, the pressure-dependent electronic structure of YbB_{6} is investigated theoretically and found to transform into a p-d overlap semimetal with small Yb mixed valency.
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Affiliation(s)
- Chang-Jong Kang
- Department of Physics, PCTP, Pohang University of Science and Technology, (POSTECH) Pohang 37673, Korea
| | - J D Denlinger
- Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720, USA
| | - J W Allen
- Department of Physics, Randall Laboratory, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Chul-Hee Min
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - F Reinert
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - B Y Kang
- School of Materials Science and Engineering, GIST, Gwangju 61005, Korea
| | - B K Cho
- School of Materials Science and Engineering, GIST, Gwangju 61005, Korea
| | - J-S Kang
- Department of Physics, The Catholic University of Korea, Bucheon 14662, Korea
| | - J H Shim
- Department of Physics, PCTP, Pohang University of Science and Technology, (POSTECH) Pohang 37673, Korea
- Department of Chemistry and Division of Advanced Nuclear Engineering, POSTECH, Pohang 37673, Korea
| | - B I Min
- Department of Physics, PCTP, Pohang University of Science and Technology, (POSTECH) Pohang 37673, Korea
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