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Ansari M, Ashraf SSZ, Tripathi P, Ahmad A. Flexural and acoustic phonon-drag thermopower and electron energy loss rate in silicene. J Phys Condens Matter 2024; 36:315503. [PMID: 38657621 DOI: 10.1088/1361-648x/ad42ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 04/24/2024] [Indexed: 04/26/2024]
Abstract
We have performed a comprehensive numerical and analytical examination of two crucial transport aspects in silicene: the phonon-drag thermopower,Sp, and the electron's energy loss rate,Fe. Specifically, our investigation is centered on their responses to out-of-plane flexural phonons and in-plane acoustic phonons in silicene, a two-dimensional allotrope of silicon as a function of electron temperature,T,and electron concentration,n,upto the room temperature. It is found that the calculated quantities have a non-monotonic dependence for the phonon modes for both parameters(T and n)considered while analytical results predict definite dependencies up to the complete low-temperature Bloch-Gruneisen (BG) regime. To provide a more comprehensive picture, we contrast the complete numerical outcomes with the approximated analytical BG results, revealing a convergence within a specific range of temperature and carrier concentration. In light of this convergence, we put forth suggestions to elucidate the underlying factors responsible for this behavior. A comparison based on the magnitude of the calculated quantities can be made from the figures between the two considered phonon modes, which clearly shows that the out-of-plane flexural phonons are effective throughout the considered temperature range. This observation leads us to posit that the dominating contribution of the out-of-plane flexural phonon modes hinges upon the deformation potential constant and phonon energy associated with the phonon mode. Our study carries significant implications for estimating the electrical and thermal properties of silicene and provides valuable insights for the development of devices based on silicene-based technologies.
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Affiliation(s)
- Meenhaz Ansari
- Interdisciplinary Nanotechnology Centre, Zakir Husain College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India
| | - S S Z Ashraf
- Department of Physics, Faculty of Science, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India
| | - P Tripathi
- Department of Applied Physics, Zakir Husain College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India
| | - A Ahmad
- Interdisciplinary Nanotechnology Centre, Zakir Husain College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India
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Sharman K, Golami O, Wein SC, Zadeh-Haghighi H, Gomes da Rocha C, Kubanek A, Simon C. A DFT study of electron-phonon interactions for the C 2C Nand V NN Bdefects in hexagonal boron nitride: investigating the role of the transition dipole direction. J Phys Condens Matter 2023. [PMID: 37311467 DOI: 10.1088/1361-648x/acde2b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Quantum emitters in two-dimensional hexagonal boron nitride (h-BN) have generated significant interest due to observations of ultra-bright emission made at room temperature. The expectation that solid-state emitters exhibit broad zero-phonon lines at elevated temperatures has been put in question by recent observations of Fourier transform (FT) limited photons emitted from h-BN flakes at room temperature. All decoupled emitters produce photons that are directed in-plane, suggesting that the dipoles are perpendicular to the h-BN plane. Motivated by the promise of an efficient and scalable source of indistinguishable photons that can operate at room temperature, we have developed an approach using density functional theory (DFT) to determine the electron- phonon coupling for defects that have in- and out-of-plane transition dipole moments. Our DFT calculations reveal that the transition dipole for the C2CNdefect is parallel to the h-BN plane, and for the VNNBdefect is perpendicular to the plane. We calculate both the phonon density of states and the electron-phonon matrix elements associated with the h-BN defective structures. We find no indication that an out-of-plane transition dipole by itself will result in the low electron-phonon coupling that is expected to produce FT-limited photons at room temperature. Our work provides direction to future DFT software developments and adds to the growing list of calculations relevant to researchers in the field of solid-state quantum information processing.
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Affiliation(s)
- Kenneth Sharman
- Physics and Astronomy , University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, CANADA
| | - Omid Golami
- University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, CANADA
| | - Stephen Christopher Wein
- Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, CANADA
| | - Hadi Zadeh-Haghighi
- Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Calgary, Alberta, T2N 1N4, CANADA
| | - Claudia Gomes da Rocha
- Physics and Astronomy, University of Calgary Faculty of Science, 2500 University Drive NW, Calgary, Alberta, T2N1N4, CANADA
| | - Alexander Kubanek
- Institut für Quantenoptik, Universitat Ulm, Hans-Kopfermann-Str. 1, 89081 Ulm, Baden-Württemberg, D-85748, GERMANY
| | - Christoph Simon
- Institute for Quantum Science and Technology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N1N4, CANADA
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Mandal S, Mallick D, Bitla Y, Ganesan R, Kumar PSA. Bulk-surface coupling in dual topological insulator Bi 1Te 1and Sb-doped Bi 1Te 1single crystals via electron-phonon interaction. J Phys Condens Matter 2023; 35:285001. [PMID: 36731168 DOI: 10.1088/1361-648x/acb89c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Recently,Bi1Te1has been proved to be a dual topological insulator (TI), a new subclass of symmetry-protected topological phases, and predicted to be higher order topological insulator (HOTI). Being a dual TI (DTI), Bi1Te1is said to host quasi-1D surface states (SSs) due to weak TI phase and topological crystalline insulating SSs at the same time. On the other hand, HOTI supports topologically protected hinge states. So,Bi1Te1is a unique platform to study the electrical signature of topological SS (TSS) of fundamentally different origins. Though there is a report of magneto-transport measurements on large-scale Bi1Te1thin films, the Bi1Te1single crystal is not studied experimentally to date. Even the doping effect in a DTI Bi1Te1is missing in the literature. In this regard, we performed the perpendicular and parallel field magneto-transport measurement on the exfoliated microflake of Bi1Te1and Sb-doped Bi1Te1single crystals, grown by the modified Bridgmann method. Ourmetallicsample shows the weak anti-localization behavior analyzed by the multi-channel Hikami-Larkin-Nagaoka equation. We observed the presence of a pair of decoupled TSS. Further, we extracted the dephasing index (β) from temperature (T)-dependence of phase coherence length (Lϕ), following the power law equation (Lϕ∝T-β). The thickness-dependent value ofβindicates the transition in the dephasing mechanism from electron-electron to electron-phonon interaction with the increase in thickness, indicating the enhancement in the strength of bulk-surface coupling. Sb-doped system shows weakened bulk-surface coupling, hinted by the reduced dephasing indices.
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Affiliation(s)
- Shoubhik Mandal
- Department of Physics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Debarghya Mallick
- Department of Physics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
- Present address: Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd, Piscataway, NJ 08854, United States of America
| | - Yugandhar Bitla
- Department of Physics, School of Physical Sciences, Central University of Rajasthan, Ajmer, Rajasthan 305817, India
| | - R Ganesan
- Department of Physics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - P S Anil Kumar
- Department of Physics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
- Center for Nanoscience and Engineering (CeNSE), Indian Institute of Science, Bengaluru, Karnataka 560012, India
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Chen Z, Lu X, Liu J, Qin W. Dimerization Triggered Magnetoelectric Coupling Effect and Magnetic Anisotropy in Organic Ternary Crystals. Small 2023; 19:e2207143. [PMID: 36543359 DOI: 10.1002/smll.202207143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/01/2022] [Indexed: 06/17/2023]
Abstract
Developing a new universal strategy to design all organic ferromagnets or multiferroics with satisfactory properties always remains challenging. In this work, ternary charge transfer crystals are fabricated to realize organic multiferroic magnetoelectric coupling effect. Through incorporating the third component into binary crystals, a dimerization between neighbor donor and acceptor is induced to form a lattice symmetry breaking, where a nonpolar to polar phase transition is ensuing to lead to a dipolar polarization. Magnetic field can effectively tune the dipolar polarization to present a magnetoelectric coupling effect. Moreover, the introduction of the third component can result in a rearrangement in molecular configuration to modify the electron-phonon interaction. As a result, anisotropic magnetism is observed due to anisotropic electron-phonon coupling in ternary crystals. Overall, this study forecasts that incorporating an appropriate third component is a potential method for designing all organic multiferroics.
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Affiliation(s)
- Zhiyan Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Xiangqian Lu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Jianqiang Liu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
| | - Wei Qin
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China
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Tao W, Zhu L, Li K, Chen C, Chen Y, Li Y, Li X, Tang J, Shang H, Zhu H. Coupled Electronic and Anharmonic Structural Dynamics for Carrier Self-Trapping in Photovoltaic Antimony Chalcogenides. Adv Sci (Weinh) 2022; 9:e2202154. [PMID: 35754307 PMCID: PMC9443444 DOI: 10.1002/advs.202202154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/20/2022] [Indexed: 06/15/2023]
Abstract
V-VI antimony chalcogenide semiconductors have shown exciting potentials for thin film photovoltaic applications. However, their solar cell efficiencies are strongly hampered by anomalously large voltage loss (>0.6 V), whose origin remains controversial so far. Herein, by combining ultrafast pump-probe spectroscopy and density functional theory (DFT) calculation, the coupled electronic and structural dynamics leading to excited state self-trapping in antimony chalcogenides with atomic level characterizations is reported. The electronic dynamics in Sb2 Se3 indicates a ≈20 ps barrierless intrinsic self-trapping, with electron localization and accompanied lattice distortion given by DFT calculations. Furthermore, impulsive vibrational coherences unveil key SbSe vibrational modes and their real-time interplay that drive initial excited state relaxation and energy dissipation toward stabilized small polaron through electron-phonon and subsequent phonon-phonon coupling. This study's findings provide conclusive evidence of carrier self-trapping arising from intrinsic lattice anharmonicity and polaronic effect in antimony chalcogenides and a new understanding on the coupled electronic and structural dynamics for redefining excited state properties in soft semiconductor materials.
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Affiliation(s)
- Weijian Tao
- State Key Laboratory of Modern Optical InstrumentationKey Laboratory of Excited‐State Materials of Zhejiang ProvinceDepartment of ChemistryZhejiang UniversityHangzhouZhejiang310027China
| | - Leilei Zhu
- State Key Laboratory of Computer ArchitectureInstitute of Computing TechnologyChinese Academy of SciencesBeijing100190China
| | - Kanghua Li
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic InformationHuazhong University of Science and TechnologyHubei430074China
| | - Chao Chen
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic InformationHuazhong University of Science and TechnologyHubei430074China
| | - Yuzhong Chen
- State Key Laboratory of Modern Optical InstrumentationKey Laboratory of Excited‐State Materials of Zhejiang ProvinceDepartment of ChemistryZhejiang UniversityHangzhouZhejiang310027China
| | - Yujie Li
- State Key Laboratory of Modern Optical InstrumentationKey Laboratory of Excited‐State Materials of Zhejiang ProvinceDepartment of ChemistryZhejiang UniversityHangzhouZhejiang310027China
| | - Xufeng Li
- State Key Laboratory of Modern Optical InstrumentationKey Laboratory of Excited‐State Materials of Zhejiang ProvinceDepartment of ChemistryZhejiang UniversityHangzhouZhejiang310027China
| | - Jiang Tang
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic InformationHuazhong University of Science and TechnologyHubei430074China
| | - Honghui Shang
- State Key Laboratory of Computer ArchitectureInstitute of Computing TechnologyChinese Academy of SciencesBeijing100190China
| | - Haiming Zhu
- State Key Laboratory of Modern Optical InstrumentationKey Laboratory of Excited‐State Materials of Zhejiang ProvinceDepartment of ChemistryZhejiang UniversityHangzhouZhejiang310027China
- Zhejiang University‐Hangzhou Global Scientific and Technological Innovation CenterHangzhou310014China
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Balin K, Wojtyniak M, Weis M, Zubko M, Wilk B, Gu R, Ruello P, Szade J. Europium Doping Impact on the Properties of MBE Grown Bi 2Te 3 Thin Film. Materials (Basel) 2020; 13:E3111. [PMID: 32668572 DOI: 10.3390/ma13143111] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 11/16/2022]
Abstract
The impact of europium doping on the electronic and structural properties of the topological insulator Bi2Te3 is studied in this paper. The crystallographic structure studied by electron diffraction and transmission microscopy confirms that grown by Molecular Beam Epitaxy (MBE) system film with the Eu content of about 3% has a trigonal structure with relatively large monocrystalline grains. The X-ray photoemission spectroscopy indicates that europium in Bi2Te3 matrix remains divalent and substitutes bismuth in a Bi2Te3 matrix. An exceptional ratio of the photoemission 4d multiplet components in Eu doped film was observed. However, some spatial inhomogeneity at the nanometer scale is revealed. Firstly, local conductivity measurements indicate that the surface conductivity is inhomogeneous and is correlated with a topographic image revealing possible coexistence of conducting surface states with insulating regions. Secondly, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) depth-profiling also shows partial chemical segregation. Such in-depth inhomogeneity has an impact on the lattice dynamics (phonon lifetime) evaluated by femtosecond spectroscopy. This unprecedented set of experimental investigations provides important insights for optimizing the process of growth of high-quality Eu-doped thin films of a Bi2Te3 topological insulator. Understanding such complex behaviors at the nanoscale level is a necessary step before considering topological insulator thin films as a component of innovative devices.
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Benedek G, Manson JR, Miret-Artés S. The Electron-Phonon Interaction of Low-Dimensional and Multi-Dimensional Materials from He Atom Scattering. Adv Mater 2020; 32:e2002072. [PMID: 32412161 DOI: 10.1002/adma.202002072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Atom scattering is becoming recognized as a sensitive probe of the electron-phonon interaction parameter λ at metal and metal-overlayer surfaces. Here, the theory is developed, linking λ to the thermal attenuation of atom scattering spectra (in particular, the Debye-Waller factor), to conducting materials of different dimensions, from quasi-1D systems such as W(110):H(1 × 1) and Bi(114), to quasi-2D layered chalcogenides, and high-dimensional surfaces such as quasicrystalline 2ML-Ba(0001)/Cu(001) and d-AlNiCo(00001). Values of λ obtained using He atoms compare favorably with known values for the bulk materials. The corresponding analysis indicates in addition, the number of layers contributing to the electron-phonon interaction, which is measured in an atom surface collision.
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Affiliation(s)
- Giorgio Benedek
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 4, Donostia-San Sebastian, 20018, Spain
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 55, Milano, 20125, Italy
| | - Joseph R Manson
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 4, Donostia-San Sebastian, 20018, Spain
- Department of Physics and Astronomy, Clemson University, Clemson, SC, 29634, USA
| | - Salvador Miret-Artés
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 4, Donostia-San Sebastian, 20018, Spain
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, Madrid, 28006, Spain
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Abstract
The manufacture of integrated circuits with single-molecule building blocks is a goal of molecular electronics. While research in the past has been limited to bulk experiments on self-assembled monolayers, advances in technology have now enabled us to fabricate single-molecule junctions. This has led to significant progress in understanding electron transport in molecular systems at the single-molecule level and the concomitant emergence of new device concepts. Here, we review recent developments in this field. We summarize the methods currently used to form metal-molecule-metal structures and some single-molecule techniques essential for characterizing molecular junctions such as inelastic electron tunnelling spectroscopy. We then highlight several important achievements, including demonstration of single-molecule diodes, transistors, and switches that make use of electrical, photo, and mechanical stimulation to control the electron transport. We also discuss intriguing issues to be addressed further in the future such as heat and thermoelectric transport in an individual molecule.
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Affiliation(s)
- Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan; E-Mail:
| | - Masateru Taniguchi
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan; E-Mail:
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