1
|
Zou WJ, Guo MX, Wong JF, Huang ZP, Chia JM, Chen WN, Wang SX, Lin KY, Young LB, Lin YHG, Yahyavi M, Wu CT, Jeng HT, Lee SF, Chang TR, Hong M, Kwo J. Enormous Berry-Curvature-Based Anomalous Hall Effect in Topological Insulator (Bi,Sb) 2Te 3 on Ferrimagnetic Europium Iron Garnet beyond 400 K. ACS NANO 2022; 16:2369-2380. [PMID: 35099945 DOI: 10.1021/acsnano.1c08663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To realize the quantum anomalous Hall effect (QAHE) at elevated temperatures, the approach of magnetic proximity effect (MPE) was adopted to break the time-reversal symmetry in the topological insulator (Bi0.3Sb0.7)2Te3 (BST) based heterostructures with a ferrimagnetic insulator europium iron garnet (EuIG) of perpendicular magnetic anisotropy. Here we demonstrate large anomalous Hall resistance (RAHE) exceeding 8 Ω (ρAHE of 3.2 μΩ·cm) at 300 K and sustaining to 400 K in 35 BST/EuIG samples, surpassing the past record of 0.28 Ω (ρAHE of 0.14 μΩ·cm) at 300 K. The large RAHE is attributed to an atomically abrupt, Fe-rich interface between BST and EuIG. Importantly, the gate dependence of the AHE loops shows no sign change with varying chemical potential. This observation is supported by our first-principles calculations via applying a gradient Zeeman field plus a contact potential on BST. Our calculations further demonstrate that the AHE in this heterostructure is attributed to the intrinsic Berry curvature. Furthermore, for gate-biased 4 nm BST on EuIG, a pronounced topological Hall effect-like (THE-like) feature coexisting with AHE is observed at the negative top-gate voltage up to 15 K. Interface tuning with theoretical calculations has realized topologically distinct phenomena in tailored magnetic TI-based heterostructures.
Collapse
Affiliation(s)
- Wei-Jhih Zou
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Meng-Xin Guo
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Jyun-Fong Wong
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Zih-Ping Huang
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jui-Min Chia
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Wei-Nien Chen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Sheng-Xin Wang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Keng-Yung Lin
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Lawrence Boyu Young
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Yen-Hsun Glen Lin
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Mohammad Yahyavi
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Chien-Ting Wu
- Materials Analysis Division, Taiwan Semiconductor Research Institute, National Applied Research Laboratories, Hsinchu 300091, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
- Physics Division, National Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Shang-Fan Lee
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Tay-Rong Chang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
- Physics Division, National Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan
- Center for Quantum Frontiers of Research and Technology (QFort), Tainan 701, Taiwan
| | - Minghwei Hong
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jueinai Kwo
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| |
Collapse
|
2
|
Huang A, Chen CH, Jeng HT. Threefold Fermions, Weyl Points, and Superconductivity in the Mirror Symmetry Lacking Semiconductor TlCd2Te4. NANOMATERIALS 2022; 12:nano12040679. [PMID: 35215007 PMCID: PMC8877975 DOI: 10.3390/nano12040679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/10/2022] [Accepted: 02/15/2022] [Indexed: 11/29/2022]
Abstract
The topological phase transition and exotic quasiparticles in materials have attracted much attention because of their potential in spintronics and mimic of elementary particles. Especially, great research interest has been paid to search for the Weyl fermions in solid-state physics. By using first-principles calculations, we predict that the multinary semiconductor alloy TlCd2Te4 exhibits threefold fermions and nodal-line fermions, which are protected by the S4 improper rotational symmetry. Moreover, owing to the lack of inversion and mirror symmetries, the threefold fermions split into Weyl fermions when the spin-orbit coupling is included. The chiral charge of Weyl points and the Z2 time-reversal topological invariant are investigated. The topological surface states, spin texture, and electron-phonon coupling analysis are presented. Our study demonstrates TlCd2Te4 as a good platform to understand topological phase transitions as well as possible coexistance of topological Weyl semimetal and superconductivity in one single material.
Collapse
Affiliation(s)
- Angus Huang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; (A.H.); (C.-H.C.)
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Chin-Hsuan Chen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; (A.H.); (C.-H.C.)
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; (A.H.); (C.-H.C.)
- Physics Division, National Center for Theoretical Sciences, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
- Correspondence:
| |
Collapse
|
3
|
Chen L, Léger Y, Loget G, Piriyev M, Jadli I, Tricot S, Rohel T, Bernard R, Beck A, Le Pouliquen J, Turban P, Schieffer P, Levallois C, Fabre B, Pedesseau L, Even J, Bertru N, Cornet C. Epitaxial III-V/Si Vertical Heterostructures with Hybrid 2D-Semimetal/Semiconductor Ambipolar and Photoactive Properties. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2101661. [PMID: 34766476 PMCID: PMC8805590 DOI: 10.1002/advs.202101661] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 09/07/2021] [Indexed: 05/28/2023]
Abstract
Hybrid materials taking advantage of the different physical properties of materials are highly attractive for numerous applications in today's science and technology. Here, it is demonstrated that epitaxial bi-domain III-V/Si are hybrid structures, composed of bulk photo-active semiconductors with 2D topological semi-metallic vertical inclusions, endowed with ambipolar properties. By combining structural, transport, and photoelectrochemical characterizations with first-principle calculations, it is shown that the bi-domain III-V/Si materials are able within the same layer to absorb light efficiently, separate laterally the photo-generated carriers, transfer them to semimetal singularities, and ease extraction of both electrons and holes vertically, leading to efficient carrier collection. Besides, the original topological properties of the 2D semi-metallic inclusions are also discussed. This comb-like heterostructure not only merges the superior optical properties of semiconductors with good transport properties of metallic materials, but also combines the high efficiency and tunability afforded by III-V inorganic bulk materials with the flexible management of nano-scale charge carriers usually offered by blends of organic materials. Physical properties of these novel hybrid heterostructures can be of great interest for energy harvesting, photonic, electronic or computing devices.
Collapse
Affiliation(s)
- Lipin Chen
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Yoan Léger
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Gabriel Loget
- Univ RennesCNRSISCR (Institut des Sciences Chimiques de Rennes)–UMR6226RennesF‐35000France
| | - Mekan Piriyev
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Imen Jadli
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Sylvain Tricot
- Univ RennesCNRSIPR (Institut de Physique de Rennes)–UMR 6251RennesF‐35000France
| | - Tony Rohel
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Rozenn Bernard
- Univ RennesCNRSIPR (Institut de Physique de Rennes)–UMR 6251RennesF‐35000France
| | - Alexandre Beck
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | | | - Pascal Turban
- Univ RennesCNRSIPR (Institut de Physique de Rennes)–UMR 6251RennesF‐35000France
| | - Philippe Schieffer
- Univ RennesCNRSIPR (Institut de Physique de Rennes)–UMR 6251RennesF‐35000France
| | | | - Bruno Fabre
- Univ RennesCNRSISCR (Institut des Sciences Chimiques de Rennes)–UMR6226RennesF‐35000France
| | - Laurent Pedesseau
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Jacky Even
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Nicolas Bertru
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| | - Charles Cornet
- Univ RennesINSA RennesCNRSInstitut FOTON–UMR 6082RennesF‐35000France
| |
Collapse
|
4
|
Schäfer T, Gallo A, Irmler A, Hummel F, Grüneis A. Surface science using coupled cluster theory via local Wannier functions and in-RPA-embedding: The case of water on graphitic carbon nitride. J Chem Phys 2021; 155:244103. [PMID: 34972356 DOI: 10.1063/5.0074936] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A first-principles study of the adsorption of a single water molecule on a layer of graphitic carbon nitride is reported employing an embedding approach for many-electron correlation methods. To this end, a plane-wave based implementation to obtain intrinsic atomic orbitals and Wannier functions for arbitrary localization potentials is presented. In our embedding scheme, the localized occupied orbitals allow for a separate treatment of short-range and long-range correlation contributions to the adsorption energy by a fragmentation of the simulation cell. In combination with unoccupied natural orbitals, the coupled cluster ansatz with single, double, and perturbative triple particle-hole excitation operators is used to capture the correlation in local fragments centered around the adsorption process. For the long-range correlation, a seamless embedding into the random phase approximation yields rapidly convergent adsorption energies with respect to the local fragment size. Convergence of computed binding energies with respect to the virtual orbital basis set is achieved employing a number of recently developed techniques. Moreover, we discuss fragment size convergence for a range of approximate many-electron perturbation theories. The obtained benchmark results are compared to a number of density functional calculations.
Collapse
Affiliation(s)
- Tobias Schäfer
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10/136, A-1040 Vienna, Austria
| | - Alejandro Gallo
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10/136, A-1040 Vienna, Austria
| | - Andreas Irmler
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10/136, A-1040 Vienna, Austria
| | - Felix Hummel
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10/136, A-1040 Vienna, Austria
| | - Andreas Grüneis
- Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10/136, A-1040 Vienna, Austria
| |
Collapse
|
5
|
Topological Phase and Quantum Anomalous Hall Effect in Ferromagnetic Transition-Metal Dichalcogenides Monolayer 1T-VSe2. NANOMATERIALS 2021; 11:nano11081998. [PMID: 34443830 PMCID: PMC8401610 DOI: 10.3390/nano11081998] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/04/2022]
Abstract
Magnetic two-dimensional (2D) van der Waals materials have attracted tremendous attention because of their high potential in spintronics. In particular, the quantum anomalous Hall (QAH) effect in magnetic 2D layers shows a very promising prospect for hosting Majorana zero modes at the topologically protected edge states in proximity to superconductors. However, the QAH effect has not yet been experimentally realized in monolayer systems to date. In this work, we study the electronic structures and topological properties of the 2D ferromagnetic transition-metal dichalcogenides (TMD) monolayer 1T−VSe2 by first-principles calculations with the Heyd–Scuseria–Ernzerhof (HSE) functional. We find that the spin-orbit coupling (SOC) opens a continuous band gap at the magnetic Weyl-like crossing point hosting the quantum anomalous Hall effect with Chern number C=2. Moreover, we demonstrate the topologically protected edge states and intrinsic (spin) Hall conductivity in this magnetic 2D TMD system. Our results indicate that 1T−VSe2 monolayer serves as a stoichiometric quantum anomalous Hall material.
Collapse
|
6
|
Hossain M, De J, Bhattacharjee J. Hybrid Atomic Orbital Basis from First Principles: Bottom-Up Mapping of Self-Energy Correction to Large Covalent Systems. J Phys Chem A 2021; 125:6805-6817. [PMID: 34324816 DOI: 10.1021/acs.jpca.1c00320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Construction of hybrid atomic orbitals is proposed as the approximate common eigenstates of finite first moment matrices. Their hybridization and orientation can be a priori tuned as per their anticipated neighborhood. Their Wannier function counterparts constructed from the Kohn-Sham (KS) single particle states constitute an orthonormal multiorbital tight binding (TB) basis resembling hybrid atomic orbitals locked to their immediate atomic neighborhood, while spanning the subspace of KS states. The proposed basis thus renders predominantly single TB parameters from first principles for each nearest neighbor bond involving no more than two orbitals irrespective of their orientation and also facilitates an easy route for the transfer of such TB parameters across isostructural systems exclusively through mapping of neighborhoods and projection of orbital charge centers. With hybridized 2s, 2p and 3s, 3p valence electrons, the spatial extent of the self-energy correction (SEC) to TB parameters in the proposed basis is found to be localized mostly within the third nearest neighborhood, thus allowing effective transfer of self-energy-corrected TB parameters from smaller reference systems to much larger target systems, with nominal additional computational cost beyond that required for explicit computation of SEC in the reference systems. The proposed approach promises inexpensive estimation of the quasi-particle structures of large covalent systems with workable accuracy.
Collapse
Affiliation(s)
- Manoar Hossain
- National Institute of Science Education and Research, Homi Bhaba National Institute, Jatni, Khurda, Bhubaneswar, 752050, Odisha, India
| | - Joydev De
- National Institute of Science Education and Research, Homi Bhaba National Institute, Jatni, Khurda, Bhubaneswar, 752050, Odisha, India
| | - Joydeep Bhattacharjee
- National Institute of Science Education and Research, Homi Bhaba National Institute, Jatni, Khurda, Bhubaneswar, 752050, Odisha, India
| |
Collapse
|
7
|
Fang Y, Kong X, Wang D, Liu J, Shang Q, Cui S. Insights into the interactions of g-C3N4/LaMnO3 hetero-junction to their structures and electronic properties by DFT calculations. J SOLID STATE CHEM 2020. [DOI: 10.1016/j.jssc.2020.121727] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
8
|
Hossain M, Bhattacharjee J. Transferability of self-energy correction in tight-binding basis constructed from first principles. J Chem Phys 2020; 153:144103. [DOI: 10.1063/5.0025653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Manoar Hossain
- National Institute of Science Education and Research, Homi Bhaba National Institute, Jatni 752050, Odisha, India
| | - Joydeep Bhattacharjee
- National Institute of Science Education and Research, Homi Bhaba National Institute, Jatni 752050, Odisha, India
| |
Collapse
|
9
|
Pandey S, Das R, Mahadevan P. Layer-Dependent Electronic Structure Changes in Transition Metal Dichalcogenides: The Microscopic Origin. ACS OMEGA 2020; 5:15169-15176. [PMID: 32637790 PMCID: PMC7331040 DOI: 10.1021/acsomega.0c01138] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 05/27/2020] [Indexed: 05/06/2023]
Abstract
We have examined the electronic structure evolution in transition metal dichalcogenides MX2 where M = Mo, W and X = S, Se, and Te. These are generally referred to as van der Waals materials on the one hand, yet one has band gap changes as large as 0.6 eV with thickness in some instances. This does not seem to be consistent with a description where the dominant interactions are van der Waals interactions. Mapping onto a tight binding model allows us to quantify the electronic structure changes, which are found to be dictated solely by interlayer hopping interactions. Different environments that an atom encounters could change the Madelung potential and therefore the onsite energies. This could happen while going from the monolayer to the bilayer as well as in cases where the stackings are different from what is found in 2H structures. These effects are quantitatively found to be negligible, enabling us to quantify the thickness-dependent electronic structure changes as arising from interlayer interactions alone.
Collapse
|
10
|
Abstract
Bismuth has been the key element in the discovery and development of topological insulator materials. Previous theoretical studies indicated that Bi is topologically trivial and it can transform into the topological phase by alloying with Sb. However, recent high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements strongly suggested a topological band structure in pure Bi, conflicting with the theoretical results. To address this issue, we studied the band structure of Bi and Sb films by ARPES and first-principles calculations. The quantum confinement effectively enlarges the energy gap in the band structure of Bi films and enables a direct visualization of the
Z
2
topological invariant of Bi. We find that Bi quantum films in topologically trivial and nontrivial phases respond differently to surface perturbations. This way, we establish experimental criteria for detecting the band topology of Bi by spectroscopic methods.
Collapse
|
11
|
Dong X, Wang M, Yan D, Peng X, Li J, Xiao W, Wang Q, Han J, Ma J, Shi Y, Yao Y. Observation of Topological Edge States at the Step Edges on the Surface of Type-II Weyl Semimetal TaIrTe 4. ACS NANO 2019; 13:9571-9577. [PMID: 31365228 DOI: 10.1021/acsnano.9b04573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Topological materials harbor topologically protected boundary states. Recently, TaIrTe4, a ternary transition-metal dichalcogenide, was identified as a type-II Weyl semimetal with the minimal nonzero number of Weyl points allowed for a time-reversal invariant Weyl semimetal. Monolayer TaIrTe4 was proposed to host topological edge states, which, however, lacks of experimental evidence. Here, we report on the topological edge states localized at the monolayer step edges of the type-II Weyl semimetal TaIrTe4 using scanning tunneling microscopy. One-dimensional electronic states that show substantial robustness against the edge irregularity are observed at the step edges. Theoretical calculations substantiate the topologically nontrivial nature of the edge states and their robustness against the edge termination and layer stacking. The observation of topological edge states at the step edges of TaIrTe4 surfaces suggests that monolayer TaIrTe4 is a two-dimensional topological insulator, providing TaIrTe4 as a promising material for topological physics and devices.
Collapse
Affiliation(s)
- Xu Dong
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Maoyuan Wang
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Dayu Yan
- Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Xianglin Peng
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Ji Li
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Wende Xiao
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Qinsheng Wang
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Junfeng Han
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Jie Ma
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| | - Youguo Shi
- Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Yugui Yao
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems and Micro-nano Centre, School of Physics , Beijing Institute of Technology , Beijing 100081 , China
| |
Collapse
|
12
|
Vogiatzis KD, Polynski MV, Kirkland JK, Townsend J, Hashemi A, Liu C, Pidko EA. Computational Approach to Molecular Catalysis by 3d Transition Metals: Challenges and Opportunities. Chem Rev 2019; 119:2453-2523. [PMID: 30376310 PMCID: PMC6396130 DOI: 10.1021/acs.chemrev.8b00361] [Citation(s) in RCA: 222] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Indexed: 12/28/2022]
Abstract
Computational chemistry provides a versatile toolbox for studying mechanistic details of catalytic reactions and holds promise to deliver practical strategies to enable the rational in silico catalyst design. The versatile reactivity and nontrivial electronic structure effects, common for systems based on 3d transition metals, introduce additional complexity that may represent a particular challenge to the standard computational strategies. In this review, we discuss the challenges and capabilities of modern electronic structure methods for studying the reaction mechanisms promoted by 3d transition metal molecular catalysts. Particular focus will be placed on the ways of addressing the multiconfigurational problem in electronic structure calculations and the role of expert bias in the practical utilization of the available methods. The development of density functionals designed to address transition metals is also discussed. Special emphasis is placed on the methods that account for solvation effects and the multicomponent nature of practical catalytic systems. This is followed by an overview of recent computational studies addressing the mechanistic complexity of catalytic processes by molecular catalysts based on 3d metals. Cases that involve noninnocent ligands, multicomponent reaction systems, metal-ligand and metal-metal cooperativity, as well as modeling complex catalytic systems such as metal-organic frameworks are presented. Conventionally, computational studies on catalytic mechanisms are heavily dependent on the chemical intuition and expert input of the researcher. Recent developments in advanced automated methods for reaction path analysis hold promise for eliminating such human-bias from computational catalysis studies. A brief overview of these approaches is presented in the final section of the review. The paper is closed with general concluding remarks.
Collapse
Affiliation(s)
| | | | - Justin K. Kirkland
- Department
of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jacob Townsend
- Department
of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Ali Hashemi
- Inorganic
Systems Engineering group, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Chong Liu
- Inorganic
Systems Engineering group, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Evgeny A. Pidko
- TheoMAT
group, ITMO University, Lomonosova 9, St. Petersburg 191002, Russia
- Inorganic
Systems Engineering group, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| |
Collapse
|
13
|
Chang T, Pletikosic I, Kong T, Bian G, Huang A, Denlinger J, Kushwaha SK, Sinkovic B, Jeng H, Valla T, Xie W, Cava RJ. Realization of a Type-II Nodal-Line Semimetal in Mg 3Bi 2. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1800897. [PMID: 30828518 PMCID: PMC6382304 DOI: 10.1002/advs.201800897] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/30/2018] [Indexed: 05/13/2023]
Abstract
Nodal-line semimetals (NLSs) represent a new type of topological semimetallic phase beyond Weyl and Dirac semimetals in the sense that they host closed loops or open curves of band degeneracies in the Brillouin zone. Parallel to the classification of type-I and type-II Weyl semimetals, there are two types of NLSs. The type-I NLS phase has been proposed and realized in many compounds, whereas the exotic type-II NLS phase that strongly violates Lorentz symmetry has remained elusive. First-principles calculations show that Mg3Bi2 is a material candidate for the type-II NLS. The band crossing is close to the Fermi level and exhibits the type-II nature of the nodal line in this material. Spin-orbit coupling generates only a small energy gap (≈35 meV) at the nodal points and does not negate the band dispersion of Mg3Bi2 that yields the type-II nodal line. Based on this prediction, Mg3Bi2 single crystals are synthesized and the presence of the type-II nodal lines in the material is confirmed. The angle-resolved photoemission spectroscopy measurements agree well with the first-principles results below the Fermi level and thus strongly suggest Mg3Bi2 as an ideal material platform for studying the as-yet unstudied properties of type-II nodal-line semimetals.
Collapse
Affiliation(s)
- Tay‐Rong Chang
- Department of PhysicsNational Cheng Kung UniversityTainan701Taiwan
| | - Ivo Pletikosic
- Department of PhysicsPrinceton UniversityPrincetonNJ08544USA
| | - Tai Kong
- Department of ChemistryPrinceton UniversityPrincetonNJ08544USA
| | - Guang Bian
- Department of Physics and AstronomyUniversity of MissouriColumbiaMO65211USA
| | - Angus Huang
- Department of PhysicsNational Tsing Hua UniversityHsinchu30013Taiwan
| | - Jonathan Denlinger
- The Advanced Light SourceLawrence Berkeley National LaboratoryBerkeleyCA94720USA
| | | | - Boris Sinkovic
- Department of PhysicsUniversity of ConnecticutStorrsCT06269USA
| | - Horny‐Tay Jeng
- Department of PhysicsNational Tsing Hua UniversityHsinchu30013Taiwan
- Institute of PhysicsAcademia SinicaTaipei11529Taiwan
- Physics DivisionNational Center for Theoretical SciencesHsinchu30013Taiwan
| | - Tonica Valla
- Condensed Matter Physics and Materials ScienceBrookhaven National LaboratoryUptonNY11973USA
| | - Weiwei Xie
- Department of ChemistryLouisiana State UniversityBaton RougeLA70803USA
| | - Robert J. Cava
- Department of PhysicsPrinceton UniversityPrincetonNJ08544USA
| |
Collapse
|
14
|
Li Y, Gu Q, Chen C, Zhang J, Liu Q, Hu X, Liu J, Liu Y, Ling L, Tian M, Wang Y, Samarth N, Li S, Zhang T, Feng J, Wang J. Nontrivial superconductivity in topological MoTe 2-x S x crystals. Proc Natl Acad Sci U S A 2018; 115:9503-9508. [PMID: 30166451 PMCID: PMC6156667 DOI: 10.1073/pnas.1801650115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Topological Weyl semimetals (TWSs) with pairs of Weyl points and topologically protected Fermi arc states have broadened the classification of topological phases and provide superior platform for study of topological superconductivity. Here we report the nontrivial superconductivity and topological features of sulfur-doped Td -phase MoTe2 with enhanced Tc compared with type-II TWS MoTe2 It is found that Td -phase S-doped MoTe2 (MoTe2-x S x , x ∼ 0.2) is a two-band s-wave bulk superconductor (∼0.13 meV and 0.26 meV), where the superconducting behavior can be explained by the s+- pairing model. Further, measurements of the quasi-particle interference (QPI) patterns and a comparison with band-structure calculations reveal the existence of Fermi arcs in MoTe2-x S x More interestingly, a relatively large superconducting gap (∼1.7 meV) is detected by scanning tunneling spectroscopy on the sample surface, showing a hint of topological nontrivial superconductivity based on the pairing of Fermi arc surface states. Our work demonstrates that the Td -phase MoTe2-x S x is not only a promising topological superconductor candidate but also a unique material for study of s+- superconductivity.
Collapse
Affiliation(s)
- Yanan Li
- International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China
- Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China
- Department of Physics, Pennsylvania State University, University Park, PA 16802
| | - Qiangqiang Gu
- International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China
- Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China
| | - Chen Chen
- Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China
- Laboratory of Advanced Materials, Fudan University, 200433 Shanghai, China
| | - Jun Zhang
- Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China
- Laboratory of Advanced Materials, Fudan University, 200433 Shanghai, China
| | - Qin Liu
- Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China
- Laboratory of Advanced Materials, Fudan University, 200433 Shanghai, China
- Science and Technology on Surface Physics and Chemistry Laboratory, 621908 Mianyang, China
| | - Xiyao Hu
- International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China
| | - Jun Liu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Hefei, Anhui, China
| | - Yi Liu
- International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China
- Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China
| | - Langsheng Ling
- High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Hefei, Anhui, China
| | - Mingliang Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Hefei, Anhui, China
| | - Yong Wang
- Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Center of Electron Microscopy, Zhejiang University, 310027 Hangzhou, China
| | - Nitin Samarth
- Department of Physics, Pennsylvania State University, University Park, PA 16802
| | - Shiyan Li
- Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China
- Laboratory of Advanced Materials, Fudan University, 200433 Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, 210093 Nanjing, China
| | - Tong Zhang
- Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China;
- Laboratory of Advanced Materials, Fudan University, 200433 Shanghai, China
- Collaborative Innovation Center of Advanced Microstructures, 210093 Nanjing, China
| | - Ji Feng
- International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China;
- Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China
- Chinese Academy of Science Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190 Beijing, China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China;
- Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China
- Chinese Academy of Science Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190 Beijing, China
| |
Collapse
|
15
|
Jin H, Li J, Wei Y, Dai Y, Guo H. Unraveling the Mechanism of Photoinduced Charge-Transfer Process in Bilayer Heterojunction. ACS APPLIED MATERIALS & INTERFACES 2018; 10:25401-25408. [PMID: 29987925 DOI: 10.1021/acsami.8b07138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Charge transfer is a fundamental process that determines the performance of solar cell devices. Although great efforts have been made, the detailed mechanism of charge-transfer process across the two-dimensional van der Waals (vdW) heterostructure remains elusive. Here, on the basis of the ab initio nonadiabatic molecular dynamics simulation, we model the photoinduced charge-transfer dynamics at the InSe/InTe vdW heterostructures. Our results show that carriers can follow either the R-scheme or Z-scheme transfer path, depending on the coupling between the interlayer states at the band-edge positions. In addition, the charge-transfer dynamics can be effectively controlled by the external parameters, such as strains and interlayer stacking configurations. The predicated electron-hole recombination lifetime in the R-scheme transfer path is up to 1.4 ns, whereas it is shortened to 1.2 ps in the Z-scheme transfer path. The proposed R-scheme and Z-scheme are further verified by the quantum transport simulations on the basis of the density functional theory (DFT) method combined with nonequilibrium Green's functions (NEGF-DFT). The analysis reveals that the system dominated by the Z-scheme shows better performance, which can be attributed to the built-in electric field that facilitates the charge transfer. Our work may pave the way for the designing of next-generation devices for light detecting and harvesting.
Collapse
Affiliation(s)
- Hao Jin
- Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy , Shenzhen University , Shenzhen 518060 , People's Republic of China
| | - Jianwei Li
- Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy , Shenzhen University , Shenzhen 518060 , People's Republic of China
| | - Yadong Wei
- Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy , Shenzhen University , Shenzhen 518060 , People's Republic of China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials , Shandong University , Jinan 250100 , People's Republic of China
| | - Hong Guo
- Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy , Shenzhen University , Shenzhen 518060 , People's Republic of China
- Centre for the Physics of Materials and Department of Physics , McGill University , Montréal H3A 2T8 , Canada
| |
Collapse
|
16
|
He J, Di Sante D, Li R, Chen XQ, Rondinelli JM, Franchini C. Tunable metal-insulator transition, Rashba effect and Weyl Fermions in a relativistic charge-ordered ferroelectric oxide. Nat Commun 2018; 9:492. [PMID: 29402881 PMCID: PMC5799170 DOI: 10.1038/s41467-017-02814-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 12/28/2017] [Indexed: 11/08/2022] Open
Abstract
Controllable metal-insulator transitions (MIT), Rashba-Dresselhaus (RD) spin splitting, and Weyl semimetals are promising schemes for realizing processing devices. Complex oxides are a desirable materials platform for such devices, as they host delicate and tunable charge, spin, orbital, and lattice degrees of freedoms. Here, using first-principles calculations and symmetry analysis, we identify an electric-field tunable MIT, RD effect, and Weyl semimetal in a known, charge-ordered, and polar relativistic oxide Ag2BiO3 at room temperature. Remarkably, a centrosymmetric BiO6 octahedral-breathing distortion induces a sizable spontaneous ferroelectric polarization through Bi3+/Bi5+ charge disproportionation, which stabilizes simultaneously the insulating phase. The continuous attenuation of the Bi3+/Bi5+ disproportionation obtained by applying an external electric field reduces the band gap and RD spin splitting and drives the phase transition from a ferroelectric RD insulator to a paraelectric Dirac semimetal, through a topological Weyl semimetal intermediate state. These findings suggest that Ag2BiO3 is a promising material for spin-orbitonic applications.
Collapse
Affiliation(s)
- Jiangang He
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna, A1080, Austria
| | - Domenico Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg, 97074, Germany
| | - Ronghan Li
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, Liaoning, China
| | - Xing-Qiu Chen
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, Liaoning, China.
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA.
| | - Cesare Franchini
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna, A1080, Austria.
| |
Collapse
|
17
|
Belopolski I, Yu P, Sanchez DS, Ishida Y, Chang TR, Zhang SS, Xu SY, Zheng H, Chang G, Bian G, Jeng HT, Kondo T, Lin H, Liu Z, Shin S, Hasan MZ. Signatures of a time-reversal symmetric Weyl semimetal with only four Weyl points. Nat Commun 2017; 8:942. [PMID: 29038436 PMCID: PMC5752680 DOI: 10.1038/s41467-017-00938-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 08/04/2017] [Indexed: 11/09/2022] Open
Abstract
Through intense research on Weyl semimetals during the past few years, we have come to appreciate that typical Weyl semimetals host many Weyl points. Nonetheless, the minimum nonzero number of Weyl points allowed in a time-reversal invariant Weyl semimetal is four. Realizing such a system is of fundamental interest and may simplify transport experiments. Recently, it was predicted that TaIrTe4 realizes a minimal Weyl semimetal. However, the Weyl points and Fermi arcs live entirely above the Fermi level, making them inaccessible to conventional angle-resolved photoemission spectroscopy (ARPES). Here, we use pump-probe ARPES to directly access the band structure above the Fermi level in TaIrTe4. We observe signatures of Weyl points and topological Fermi arcs. Combined with ab initio calculation, our results show that TaIrTe4 is a Weyl semimetal with the minimum number of four Weyl points. Our work provides a simpler platform for accessing exotic transport phenomena arising in Weyl semimetals.Weyl semimetals are interesting because they are characterized by topological invariants, but specific examples discovered to date tend to have complicated band structures with many Weyl points. Here, the authors show that TaIrTe4 has only four Weyl points, the minimal number required by time-reversal symmetry.
Collapse
Affiliation(s)
- Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA.
| | - Peng Yu
- Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Daniel S Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Yukiaki Ishida
- Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba, 277-8581, Japan
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.,Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan
| | - Songtian S Zhang
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA.,Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.,Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Takeshi Kondo
- Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba, 277-8581, Japan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Zheng Liu
- Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.,NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore.,CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Shik Shin
- Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba, 277-8581, Japan
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA. .,Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ, 08544, USA.
| |
Collapse
|
18
|
Peng L, Yuan Y, Li G, Yang X, Xian JJ, Yi CJ, Shi YG, Fu YS. Observation of topological states residing at step edges of WTe 2. Nat Commun 2017; 8:659. [PMID: 28939864 PMCID: PMC5610310 DOI: 10.1038/s41467-017-00745-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/25/2017] [Indexed: 12/03/2022] Open
Abstract
Topological states emerge at the boundary of solids as a consequence of the nontrivial topology of the bulk. Recently, theory predicts a topological edge state on single layer transition metal dichalcogenides with 1T' structure. However, its existence still lacks experimental proof. Here, we report the direct observations of the topological states at the step edge of WTe2 by spectroscopic-imaging scanning tunneling microscopy. A one-dimensional electronic state residing at the step edge of WTe2 is observed, which exhibits remarkable robustness against edge imperfections. First principles calculations rigorously verify the edge state has a topological origin, and its topological nature is unaffected by the presence of the substrate. Our study supports the existence of topological edge states in 1T'-WTe2, which may envision in-depth study of its topological physics and device applications.Two-dimensional topological insulators support edge conduction electrons but its realization in real materials is rare. Here, Peng et al. report the direct observation of topological states at the step edge of WTe2.
Collapse
Affiliation(s)
- Lang Peng
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuan Yuan
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Gang Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 200031, China.
- Institute of Solid State Physics, Vienna University of Technology, A-1040, Vienna, Austria.
| | - Xing Yang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jing-Jing Xian
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Chang-Jiang Yi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, China
| | - You-Guo Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, China
| | - Ying-Shuang Fu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China.
| |
Collapse
|
19
|
Okada Y, Shiau SY, Chang TR, Chang G, Kobayashi M, Shimizu R, Jeng HT, Shiraki S, Kumigashira H, Bansil A, Lin H, Hitosugi T. Quasiparticle Interference on Cubic Perovskite Oxide Surfaces. PHYSICAL REVIEW LETTERS 2017; 119:086801. [PMID: 28952762 DOI: 10.1103/physrevlett.119.086801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Indexed: 06/07/2023]
Abstract
We report the observation of coherent surface states on cubic perovskite oxide SrVO_{3}(001) thin films through spectroscopic-imaging scanning tunneling microscopy. A direct link between the observed quasiparticle interference patterns and the formation of a d_{xy}-derived surface state is supported by first-principles calculations. We show that the apical oxygens on the topmost VO_{2} plane play a critical role in controlling the coherent surface state via modulating orbital state.
Collapse
Affiliation(s)
- Yoshinori Okada
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Shiue-Yuan Shiau
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Masaki Kobayashi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Ryota Shimizu
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Susumu Shiraki
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Hiroshi Kumigashira
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Taro Hitosugi
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
- Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| |
Collapse
|
20
|
Chang TR, Xu SY, Sanchez DS, Tsai WF, Huang SM, Chang G, Hsu CH, Bian G, Belopolski I, Yu ZM, Yang SA, Neupert T, Jeng HT, Lin H, Hasan MZ. Type-II Symmetry-Protected Topological Dirac Semimetals. PHYSICAL REVIEW LETTERS 2017; 119:026404. [PMID: 28753359 DOI: 10.1103/physrevlett.119.026404] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Indexed: 06/07/2023]
Abstract
The recent proposal of the type-II Weyl semimetal state has attracted significant interest. In this Letter, we propose the concept of the three-dimensional type-II Dirac fermion and theoretically identify this new symmetry-protected topological state in the large family of transition-metal icosagenides, MA_{3} (M=V, Nb, Ta; A=Al, Ga, In). We show that the VAl_{3} family features a pair of strongly Lorentz-violating type-II Dirac nodes and that each Dirac node can be split into four type-II Weyl nodes with chiral charge ±1 via symmetry breaking. Furthermore, we predict that the Landau level spectrum arising from the type-II Dirac fermions in VAl_{3} is distinct from that of known Dirac or Weyl semimetals. We also demonstrate a topological phase transition from a type-II Dirac semimetal to a quadratic Weyl semimetal or a topological crystalline insulator via crystalline distortions.
Collapse
Affiliation(s)
- Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel S Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Wei-Feng Tsai
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Shin-Ming Huang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Chuang-Han Hsu
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Zhi-Ming Yu
- School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Titus Neupert
- Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| |
Collapse
|
21
|
Di Sante D, Das PK, Bigi C, Ergönenc Z, Gürtler N, Krieger JA, Schmitt T, Ali MN, Rossi G, Thomale R, Franchini C, Picozzi S, Fujii J, Strocov VN, Sangiovanni G, Vobornik I, Cava RJ, Panaccione G. Three-Dimensional Electronic Structure of the Type-II Weyl Semimetal WTe_{2}. PHYSICAL REVIEW LETTERS 2017; 119:026403. [PMID: 28753342 DOI: 10.1103/physrevlett.119.026403] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Indexed: 06/07/2023]
Abstract
By combining bulk sensitive soft-x-ray angular-resolved photoemission spectroscopy and first-principles calculations we explored the bulk electron states of WTe_{2}, a candidate type-II Weyl semimetal featuring a large nonsaturating magnetoresistance. Despite the layered geometry suggesting a two-dimensional electronic structure, we directly observe a three-dimensional electronic dispersion. We report a band dispersion in the reciprocal direction perpendicular to the layers, implying that electrons can also travel coherently when crossing from one layer to the other. The measured Fermi surface is characterized by two well-separated electron and hole pockets at either side of the Γ point, differently from previous more surface sensitive angle-resolved photoemission spectroscopy experiments that additionally found a pronounced quasiparticle weight at the zone center. Moreover, we observe a significant sensitivity of the bulk electronic structure of WTe_{2} around the Fermi level to electronic correlations and renormalizations due to self-energy effects, previously neglected in first-principles descriptions.
Collapse
Affiliation(s)
- Domenico Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
| | - Pranab Kumar Das
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
- International Centre for Theoretical Physics (ICTP), Strada Costiera 11, I-34100 Trieste, Italy
| | - C Bigi
- Dipartimento di Fisica, Universitá di Milano, Via Celoria 16, I-20133 Milano, Italy
| | - Z Ergönenc
- Computational Materials Physics, University of Vienna, Sensengasse 8/8, A-1090 Vienna, Austria
| | - N Gürtler
- Computational Materials Physics, University of Vienna, Sensengasse 8/8, A-1090 Vienna, Austria
| | - J A Krieger
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
- Laboratorium für Festkörperphysik, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - T Schmitt
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen, Switzerland
| | - M N Ali
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - G Rossi
- Dipartimento di Fisica, Universitá di Milano, Via Celoria 16, I-20133 Milano, Italy
| | - R Thomale
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
| | - C Franchini
- Computational Materials Physics, University of Vienna, Sensengasse 8/8, A-1090 Vienna, Austria
| | - S Picozzi
- Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila 67100, Italy
| | - J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - V N Strocov
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen, Switzerland
| | - G Sangiovanni
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
| | - I Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - R J Cava
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - G Panaccione
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| |
Collapse
|
22
|
Sutter D, Fatuzzo CG, Moser S, Kim M, Fittipaldi R, Vecchione A, Granata V, Sassa Y, Cossalter F, Gatti G, Grioni M, Rønnow HM, Plumb NC, Matt CE, Shi M, Hoesch M, Kim TK, Chang TR, Jeng HT, Jozwiak C, Bostwick A, Rotenberg E, Georges A, Neupert T, Chang J. Hallmarks of Hunds coupling in the Mott insulator Ca 2RuO 4. Nat Commun 2017; 8:15176. [PMID: 28474681 PMCID: PMC5424259 DOI: 10.1038/ncomms15176] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/03/2017] [Indexed: 11/20/2022] Open
Abstract
A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realized in Ca2RuO4. Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic structure. Here we provide—using angle-resolved photoemission electron spectroscopy—the band structure of the paramagnetic insulating phase of Ca2RuO4 and show how it features several distinct energy scales. Comparison to a simple analysis of atomic multiplets provides a quantitative estimate of the Hund's coupling J=0.4 eV. Furthermore, the experimental spectra are in good agreement with electronic structure calculations performed with Dynamical Mean-Field Theory. The crystal field stabilization of the dxy orbital due to c-axis contraction is shown to be essential to explain the insulating phase. These results underscore the importance of multi-band physics, Coulomb interaction and Hund's coupling that together generate the Mott insulating state of Ca2RuO4. Detailed knowledge of the low-energy electronic structure is required to understand the Mott insulating phase of Ca2RuO4. Here, Sutter et al. provide directly the experimental band structure of the paramagnetic insulating phase of Ca2RuO4 and unveil the electronic origin of its Mott phase.
Collapse
Affiliation(s)
- D Sutter
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| | - C G Fatuzzo
- Institute of Physics, École Polytechnique Fedérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - S Moser
- Advanced Light Source (ALS), Berkeley, California 94720, USA
| | - M Kim
- College de France, Paris Cedex 05 75231, France.,Centre de Physique Théorique, Ecole Polytechnique, CNRS, Univ Paris-Saclay, Palaiseau 91128, France
| | - R Fittipaldi
- CNR-SPIN, Fisciano, Salerno I-84084, Italy.,Dipartimento di Fisica 'E.R. Caianiello', Università di Salerno, Fisciano, Salerno I-84084, Italy
| | - A Vecchione
- CNR-SPIN, Fisciano, Salerno I-84084, Italy.,Dipartimento di Fisica 'E.R. Caianiello', Università di Salerno, Fisciano, Salerno I-84084, Italy
| | - V Granata
- CNR-SPIN, Fisciano, Salerno I-84084, Italy.,Dipartimento di Fisica 'E.R. Caianiello', Università di Salerno, Fisciano, Salerno I-84084, Italy
| | - Y Sassa
- Department of Physics and Astronomy, Uppsala University, Uppsala S-75121, Sweden
| | - F Cossalter
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| | - G Gatti
- Institute of Physics, École Polytechnique Fedérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - M Grioni
- Institute of Physics, École Polytechnique Fedérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - H M Rønnow
- Institute of Physics, École Polytechnique Fedérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI CH-5232, Switzerland
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - T-R Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.,Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - H-T Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.,Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - C Jozwiak
- Advanced Light Source (ALS), Berkeley, California 94720, USA
| | - A Bostwick
- Advanced Light Source (ALS), Berkeley, California 94720, USA
| | - E Rotenberg
- Advanced Light Source (ALS), Berkeley, California 94720, USA
| | - A Georges
- College de France, Paris Cedex 05 75231, France.,Centre de Physique Théorique, Ecole Polytechnique, CNRS, Univ Paris-Saclay, Palaiseau 91128, France.,Department of Quantum Matter Physics, University of Geneva, Geneva 4 1211, Switzerland
| | - T Neupert
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| | - J Chang
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| |
Collapse
|
23
|
Belopolski I, Sanchez DS, Ishida Y, Pan X, Yu P, Xu SY, Chang G, Chang TR, Zheng H, Alidoust N, Bian G, Neupane M, Huang SM, Lee CC, Song Y, Bu H, Wang G, Li S, Eda G, Jeng HT, Kondo T, Lin H, Liu Z, Song F, Shin S, Hasan MZ. Discovery of a new type of topological Weyl fermion semimetal state in Mo xW 1-xTe 2. Nat Commun 2016; 7:13643. [PMID: 27917858 PMCID: PMC5150217 DOI: 10.1038/ncomms13643] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/21/2016] [Indexed: 01/15/2023] Open
Abstract
The recent discovery of a Weyl semimetal in TaAs offers the first Weyl fermion observed in nature and dramatically broadens the classification of topological phases. However, in TaAs it has proven challenging to study the rich transport phenomena arising from emergent Weyl fermions. The series MoxW1−xTe2 are inversion-breaking, layered, tunable semimetals already under study as a promising platform for new electronics and recently proposed to host Type II, or strongly Lorentz-violating, Weyl fermions. Here we report the discovery of a Weyl semimetal in MoxW1−xTe2 at x=25%. We use pump-probe angle-resolved photoemission spectroscopy (pump-probe ARPES) to directly observe a topological Fermi arc above the Fermi level, demonstrating a Weyl semimetal. The excellent agreement with calculation suggests that MoxW1−xTe2 is a Type II Weyl semimetal. We also find that certain Weyl points are at the Fermi level, making MoxW1−xTe2 a promising platform for transport and optics experiments on Weyl semimetals. A Type II Weyl fermion semimetal has been predicted in MoxW1−xTe2, but it awaits experimental evidence. Here, Belopolski et al. observe a topological Fermi arc in MoxW1−xTe2, showing it originates from a Type II Weyl fermion and offering a new platform to study novel transport phenomena in Weyl semimetals.
Collapse
Affiliation(s)
- Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel S Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yukiaki Ishida
- The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - Xingchen Pan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Peng Yu
- Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Madhab Neupane
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
| | - You Song
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Haijun Bu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Guanghou Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Shisheng Li
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
| | - Goki Eda
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.,Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.,Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Takeshi Kondo
- The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
| | - Zheng Liu
- Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.,NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.,CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553, Singapore
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Shik Shin
- The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.,Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA
| |
Collapse
|
24
|
The electronic, structural and magnetic properties of La(1-1/3)Sr(1/3)MnO3 film with oxygen vacancy: a first principles investigation. Sci Rep 2016; 6:22422. [PMID: 26927290 PMCID: PMC4772481 DOI: 10.1038/srep22422] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/15/2016] [Indexed: 11/08/2022] Open
Abstract
We have systematically investigated the influence of oxygen vacancy defects on the structural, electronic and magnetic properties of La(1-x)Sr(x)MnO3 (x = 1/3) film by means of ab initio calculations using bare GGA as well as GGA+U formalism, in the latter of which, the on-site Coulombic repulsion parameter U for Mn 3d orbital has been determined by the linear response theory. It is revealed that the introduction of the vacancy defects causes prominent structural changes including the distortion of MnO6 octahedra and local structural deformation surrounding the oxygen vacancy. The GGA+U formalism yields a significantly larger structural change than the bare GGA method, surprisingly in contrast with the general notion that the inclusion of Hubbard U parameter exerts little influence on structural properties. The distortion of MnO6 octahedra leads to a corresponding variation in the hybridization between Mn 3d and O 2p, which gets strengthened if the Mn-O distance becomes smaller and vice versa. The magnetic moments of the Mn atoms located in three typical sites of the vacancy-containing supercell are all larger than those in the pristine system. We have characterized the O-vacancy defect as a hole-type defect that forms a negative charge center, attracting electrons.
Collapse
|
25
|
Chang TR, Xu SY, Chang G, Lee CC, Huang SM, Wang B, Bian G, Zheng H, Sanchez DS, Belopolski I, Alidoust N, Neupane M, Bansil A, Jeng HT, Lin H, Zahid Hasan M. Prediction of an arc-tunable Weyl Fermion metallic state in Mo(x)W(1-x)Te2. Nat Commun 2016; 7:10639. [PMID: 26875819 PMCID: PMC4756349 DOI: 10.1038/ncomms10639] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 01/07/2016] [Indexed: 12/25/2022] Open
Abstract
A Weyl semimetal is a new state of matter that hosts Weyl fermions as emergent quasiparticles. The Weyl fermions correspond to isolated points of bulk band degeneracy, Weyl nodes, which are connected only through the crystal's boundary by exotic Fermi arcs. The length of the Fermi arc gives a measure of the topological strength, because the only way to destroy the Weyl nodes is to annihilate them in pairs in the reciprocal space. To date, Weyl semimetals are only realized in the TaAs class. Here, we propose a tunable Weyl state in Mo(x)W(1-x)Te2 where Weyl nodes are formed by touching points between metallic pockets. We show that the Fermi arc length can be changed as a function of Mo concentration, thus tuning the topological strength. Our results provide an experimentally feasible route to realizing Weyl physics in the layered compound Mo(x)W(1-x)Te2, where non-saturating magneto-resistance and pressure-driven superconductivity have been observed.
Collapse
Affiliation(s)
- Tay-Rong Chang
- Department of Physics, National Tsing Hua University, 30013 Hsinchu, Taiwan
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - BaoKai Wang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
- Department of Physics, Northeastern University, Boston, 02115 Massachusetts, USA
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Daniel S. Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Madhab Neupane
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
- Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos, 87545 New Mexico, USA
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, 02115 Massachusetts, USA
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, 30013 Hsinchu, Taiwan
- Institute of Physics, Academia Sinica, 11529 Taipei, Taiwan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - M. Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
- Princeton Center for Complex Materials, Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, 08544 New Jersey, USA
| |
Collapse
|
26
|
Zhou L, Kou L, Sun Y, Felser C, Hu F, Shan G, Smith SC, Yan B, Frauenheim T. New Family of Quantum Spin Hall Insulators in Two-dimensional Transition-Metal Halide with Large Nontrivial Band Gaps. NANO LETTERS 2015; 15:7867-7872. [PMID: 26524118 DOI: 10.1021/acs.nanolett.5b02617] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Topological insulators (TIs) are promising for achieving dissipationless transport devices due to the robust gapless states inside the insulating bulk gap. However, currently realized two-dimensional (2D) TIs, quantum spin Hall (QSH) insulators, suffer from ultrahigh vacuum and extremely low temperature. Thus, seeking for desirable QSH insulators with high feasibility of experimental preparation and large nontrivial gap is of great importance for wide applications in spintronics. On the basis of the first-principles calculations, we predict a novel family of 2D QSH insulators in transition-metal halide MX (M = Zr, Hf; X = Cl, Br, and I) monolayers, especially, which is the first case based on transition-metal halide-based QSH insulators. MX family has the large nontrivial gaps of 0.12-0.4 eV, comparable with bismuth (111) bilayer (0.2 eV), stanene (0.3 eV), and larger than ZrTe5 (0.1 eV) monolayers and graphene-based sandwiched heterstructures (30-70 meV). Their corresponding 3D bulk materials are weak topological insulators from stacking QSH layers, and some of bulk compounds have already been synthesized in experiment. The mechanism for 2D QSH effect in this system originates from a novel d-d band inversion, significantly different from conventional band inversion between s-p, p-p, or d-p orbitals. The realization of pure layered MX monolayers may be prepared by exfoliation from their 3D bulk phases, thus holding great promise for nanoscale device applications and stimulating further efforts on transition metal-based QSH materials.
Collapse
Affiliation(s)
- Liujiang Zhou
- Bremen Center for Computational Materials Science, University of Bremen , Am Falturm 1, 28359 Bremen, Germany
| | - Liangzhi Kou
- Integrated Materials Design Centre, School of Chemical Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Yan Sun
- Max Planck Institute for Chemical Physics of Solids , Noethnitzer Strasse 40, 01187 Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids , Noethnitzer Strasse 40, 01187 Dresden, Germany
| | - Feiming Hu
- Bremen Center for Computational Materials Science, University of Bremen , Am Falturm 1, 28359 Bremen, Germany
| | - Guangcun Shan
- Department of Physics and Materials Science and Center for Functional Photonics, City University of Hong Kong , Kowloon Tong, Hong Kong SAR
| | - Sean C Smith
- Integrated Materials Design Centre, School of Chemical Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Binghai Yan
- Max Planck Institute for Chemical Physics of Solids , Noethnitzer Strasse 40, 01187 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems , Noethnitzer Strasse 38, 01187 Dresden, Germany
| | - Thomas Frauenheim
- Bremen Center for Computational Materials Science, University of Bremen , Am Falturm 1, 28359 Bremen, Germany
| |
Collapse
|
27
|
Li G, Yan B, Thomale R, Hanke W. Topological nature and the multiple Dirac cones hidden in Bismuth high-Tc superconductors. Sci Rep 2015; 5:10435. [PMID: 26014056 PMCID: PMC4444835 DOI: 10.1038/srep10435] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 04/13/2015] [Indexed: 12/01/2022] Open
Abstract
Recent theoretical studies employing density-functional theory have predicted BaBiO3 (when doped with electrons) and YBiO3 to become a topological insulator (TI) with a large topological gap (~0.7 eV). This, together with the natural stability against surface oxidation, makes the Bismuth-Oxide family of special interest for possible applications in quantum information and spintronics. The central question, we study here, is whether the hole-doped Bismuth Oxides, i.e. Ba1-xKxBiO3 and BaPb1-xBixO3, which are “high-Tc” bulk superconducting near 30 K, additionally display in the further vicinity of their Fermi energy EF a topological gap with a Dirac-type of topological surface state. Our electronic structure calculations predict the K-doped family to emerge as a TI, with a topological gap above EF. Thus, these compounds can become superconductors with hole-doping and potential TIs with additional electron doping. Furthermore, we predict the Bismuth-Oxide family to contain an additional Dirac cone below EF for further hole doping, which manifests these systems to be candidates for both electron- and hole-doped topological insulators.
Collapse
Affiliation(s)
- Gang Li
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
| | - Binghai Yan
- 1] Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany [2] Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - Ronny Thomale
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
| | - Werner Hanke
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
| |
Collapse
|
28
|
Polfus JM, Xing W, Sunding MF, Hanetho SM, Dahl PI, Larring Y, Fontaine ML, Bredesen R. Doping strategies for increased oxygen permeability of CaTiO3 based membranes. J Memb Sci 2015. [DOI: 10.1016/j.memsci.2015.02.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
29
|
Wang G, Marie X, Gerber I, Amand T, Lagarde D, Bouet L, Vidal M, Balocchi A, Urbaszek B. Giant enhancement of the optical second-harmonic emission of WSe(2) monolayers by laser excitation at exciton resonances. PHYSICAL REVIEW LETTERS 2015; 114:097403. [PMID: 25793850 DOI: 10.1103/physrevlett.114.097403] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Indexed: 05/22/2023]
Abstract
We show that the light-matter interaction in monolayer WSe_{2} is strongly enhanced when the incoming electromagnetic wave is in resonance with the energy of the exciton states of strongly Coulomb bound electron-hole pairs below the electronic band gap. We perform second harmonic generation (SHG) spectroscopy as a function of laser energy and polarization at T=4 K. At the exciton resonance energies we record an enhancement by up to 3 orders of magnitude of the SHG efficiency, due to the unusual combination of electric dipole and magnetic dipole transitions. The energy and parity of the exciton states showing the strong resonance effects are identified in 1- and 2-photon photoluminescence excitation experiments, corroborated by first principles calculations. Targeting the identified exciton states in resonant 2-photon excitation allows us to maximize k-valley coherence and polarization.
Collapse
Affiliation(s)
- G Wang
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - X Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - I Gerber
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - T Amand
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - D Lagarde
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - L Bouet
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - M Vidal
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - A Balocchi
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| | - B Urbaszek
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue de Rangueil, 31077 Toulouse, France
| |
Collapse
|
30
|
Tunable ferroelectric polarization and its interplay with spin-orbit coupling in tin iodide perovskites. Nat Commun 2014; 5:5900. [PMID: 25533044 DOI: 10.1038/ncomms6900] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 11/19/2014] [Indexed: 12/22/2022] Open
Abstract
Ferroelectricity is a potentially crucial issue in halide perovskites, breakthrough materials in photovoltaic research. Using density functional theory simulations and symmetry analysis, we show that the lead-free perovskite iodide (FA)SnI3, containing the planar formamidinium cation FA, (NH2CHNH2)(+), is ferroelectric. In fact, the perpendicular arrangement of FA planes, leading to a 'weak' polarization, is energetically more stable than parallel arrangements of FA planes, being either antiferroelectric or 'strong' ferroelectric. Moreover, we show that the 'weak' and 'strong' ferroelectric states with the polar axis along different crystallographic directions are energetically competing. Therefore, at least at low temperatures, an electric field could stabilize different states with the polarization rotated by π/4, resulting in a highly tunable ferroelectricity appealing for multistate logic. Intriguingly, the relatively strong spin-orbit coupling in noncentrosymmetric (FA)SnI3 gives rise to a co-existence of Rashba and Dresselhaus effects and to a spin texture that can be induced, tuned and switched by an electric field controlling the ferroelectric state.
Collapse
|
31
|
Zhai X, Cheng L, Liu Y, Schlepütz CM, Dong S, Li H, Zhang X, Chu S, Zheng L, Zhang J, Zhao A, Hong H, Bhattacharya A, Eckstein JN, Zeng C. Correlating interfacial octahedral rotations with magnetism in (LaMnO3+δ)N/(SrTiO3)N superlattices. Nat Commun 2014; 5:4283. [PMID: 25005724 DOI: 10.1038/ncomms5283] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 06/03/2014] [Indexed: 11/10/2022] Open
Abstract
Lattice distortion due to oxygen octahedral rotations have a significant role in mediating the magnetism in oxides, and recently attracts a lot of interests in the study of complex oxides interface. However, the direct experimental evidence for the interrelation between octahedral rotation and magnetism at interface is scarce. Here we demonstrate that interfacial octahedral rotation are closely linked to the strongly modified ferromagnetism in (LaMnO3+δ)N/(SrTiO3)N superlattices. The maximized ferromagnetic moment in the N=6 superlattice is accompanied by a metastable structure (space group Imcm) featuring minimal octahedral rotations (a(-)a(-)c(-), α~4.2°, γ~0.5°). Quenched ferromagnetism for N<4 superlattices is correlated to a substantially enhanced c axis octahedral rotation (a(-)a(-)c(-), α~3.8°, γ~8° for N=2). Monte-Carlo simulation based on double-exchange model qualitatively reproduces the experimental observation, confirming the correlation between octahedral rotation and magnetism. Our study demonstrates that engineering superlattices with controllable interfacial structures can be a feasible new route in realizing functional magnetic materials.
Collapse
Affiliation(s)
- Xiaofang Zhai
- 1] Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [2] Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Long Cheng
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yang Liu
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | | | - Shuai Dong
- Department of Physics, Southeast University, Nanjing 211189, China
| | - Hui Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaoqiang Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shengqi Chu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Lirong Zheng
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Aidi Zhao
- 1] Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [2] Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hawoong Hong
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Anand Bhattacharya
- Materials Science Division and Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - James N Eckstein
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Changgan Zeng
- 1] Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [2] Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| |
Collapse
|
32
|
Oxidation of ethane to ethanol by N2O in a metal-organic framework with coordinatively unsaturated iron(II) sites. Nat Chem 2014; 6:590-5. [PMID: 24950328 DOI: 10.1038/nchem.1956] [Citation(s) in RCA: 309] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 04/14/2014] [Indexed: 12/23/2022]
Abstract
Enzymatic haem and non-haem high-valent iron-oxo species are known to activate strong C-H bonds, yet duplicating this reactivity in a synthetic system remains a formidable challenge. Although instability of the terminal iron-oxo moiety is perhaps the foremost obstacle, steric and electronic factors also limit the activity of previously reported mononuclear iron(IV)-oxo compounds. In particular, although nature's non-haem iron(IV)-oxo compounds possess high-spin S = 2 ground states, this electronic configuration has proved difficult to achieve in a molecular species. These challenges may be mitigated within metal-organic frameworks that feature site-isolated iron centres in a constrained, weak-field ligand environment. Here, we show that the metal-organic framework Fe2(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) and its magnesium-diluted analogue, Fe0.1Mg1.9(dobdc), are able to activate the C-H bonds of ethane and convert it into ethanol and acetaldehyde using nitrous oxide as the terminal oxidant. Electronic structure calculations indicate that the active oxidant is likely to be a high-spin S = 2 iron(IV)-oxo species.
Collapse
|
33
|
Di Sante D, Stroppa A, Picozzi S. Structural, electronic and ferroelectric properties of croconic acid crystal: a DFT study. Phys Chem Chem Phys 2012; 14:14673-81. [DOI: 10.1039/c2cp42127e] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|