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Leng P, Joseph NB, Cao X, Qian Y, Li Z, Ma Q, Ai L, Banerjee A, Zhang Y, Jia Z, Zhang Y, Xi C, Pi L, Narayan A, Zhang J, Xiu F. Thickness-Dependent Magnetic Breakdown in ZrSiSe Nanoplates. NANO LETTERS 2024; 24:5125-5131. [PMID: 38639405 DOI: 10.1021/acs.nanolett.3c04919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
We report a study of thickness-dependent interband and intraband magnetic breakdown by thermoelectric quantum oscillations in ZrSiSe nanoplates. Under high magnetic fields of up to 30 T, quantum oscillations arising from degenerated hole pockets were observed in thick ZrSiSe nanoplates. However, when decreasing the thickness, plentiful multifrequency quantum oscillations originating from hole and electron pockets are captured. These multiple frequencies can be explained by the emergent interband magnetic breakdown enclosing individual hole and electron pockets and intraband magnetic breakdown within spin-orbit coupling (SOC) induced saddle-shaped electron pockets, resulting in the enhanced contribution to thermal transport in thin ZrSiSe nanoplates. These experimental frequencies agree well with theoretical calculations of the intriguing tunneling processes. Our results introduce a new member of magnetic breakdown to the field and open up a dimension for modulating magnetic breakdown, which holds fundamental significance for both low-dimensional topological materials and the physics of magnetic breakdown.
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Affiliation(s)
- Pengliang Leng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
| | - Nesta Benno Joseph
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Xiangyu Cao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
| | - Yingcai Qian
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Qiang Ma
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
| | - Linfeng Ai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
| | - Ayan Banerjee
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Yuda Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
| | - Zehao Jia
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
| | - Yong Zhang
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Chuanying Xi
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Li Pi
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Awadhesh Narayan
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Jinglei Zhang
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai, 200232, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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2
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Wang T, Yu X. Helicity-Sensitive Terahertz Detection in Monolayer 1T'-WTe 2. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38619870 DOI: 10.1021/acsami.3c18898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Valleytronics, identified as electronic properties of the energy band extrema in momentum space, has been intensively revived following the emergence of two-dimensional transition metal dichalcogenides (TMDCs) as their valley information can be controlled and probed through the spin angular momentum of light. Previous optical investigations of valleytronics have been limited to the visible/near-infrared spectral regime through which the carriers of most TMDCs can be excited. Monolayer 1T'-WTe2 with broken time-reversal symmetry provides a fertile platform to study the long-wavelength photonic properties in different valleys. Here, we employed a circularly polarized terahertz (THz) laser to selectively excite the valley of monolayer 1T'-WTe2 and demonstrate that the helicity-dependent photoresponse is generated via the photogalvanic effect (PGE). We also observed that the photocurrent is controlled by circular polarization and the external electric field. Because of the tunable Berry curvature dipole derived from the nontrivial wave functions near the inverted gap edge in monolayer WTe2, the bandgap can be tuned efficiently. Our results provide a versatile venue for controlling, detecting, and processing valleytronics and applications in on-chip THz imaging and quantum information processing.
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Affiliation(s)
- Ting Wang
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, China
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Xuechao Yu
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, China
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
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Pogna EAA, Pistore V, Viti L, Li L, Davies AG, Linfield EH, Vitiello MS. Near-field detection of gate-tunable anisotropic plasmon polaritons in black phosphorus at terahertz frequencies. Nat Commun 2024; 15:2373. [PMID: 38490988 PMCID: PMC10943022 DOI: 10.1038/s41467-024-45264-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/18/2024] [Indexed: 03/18/2024] Open
Abstract
Polaritons in two-dimensional layered crystals offer an effective solution to confine, enhance and manipulate terahertz (THz) frequency electromagnetic waves at the nanoscale. Recently, strong THz field confinement has been achieved in a graphene-insulator-metal structure, exploiting THz plasmon polaritons (PPs) with strongly reduced wavelength (λp ≈ λ0/66) compared to the photon wavelength λ0. However, graphene PPs propagate isotropically, complicating the directional control of the THz field, which, on the contrary, can be achieved exploiting anisotropic layered crystals, such as orthorhombic black-phosphorus. Here, we detect PPs, at THz frequencies, in hBN-encapsulated black phosphorus field effect transistors through THz near-field photocurrent nanoscopy. The real-space mapping of the thermoelectrical near-field photocurrents reveals deeply sub-wavelength THz PPs (λp ≈ λ0/76), with dispersion tunable by electrostatic control of the carrier density. The in-plane anisotropy of the dielectric response results into anisotropic polariton propagation along the armchair and zigzag crystallographic axes of black-phosphorus. The achieved directional subwavelength light confinement makes this material system a versatile platform for sensing and quantum technology based on nonlinear optics.
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Affiliation(s)
- Eva A A Pogna
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy.
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Valentino Pistore
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy
| | - Leonardo Viti
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy
| | - Lianhe Li
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - A Giles Davies
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Edmund H Linfield
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Miriam S Vitiello
- NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, P. San Silvestro 12, 56127, Pisa, Italy.
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4
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Ozdemir I, Holleitner AW, Kastl C, Aktürk OÜ. Thickness and defect dependent electronic, optical and thermoelectric features of [Formula: see text]. Sci Rep 2022; 12:12756. [PMID: 35882909 PMCID: PMC9325696 DOI: 10.1038/s41598-022-16899-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/18/2022] [Indexed: 11/08/2022] Open
Abstract
Transition metal dichalcogenides (TMDs) receive significant attention due to their outstanding electronic and optical properties. In this study, we investigate the electronic, optical, and thermoelectric properties of single and few layer [Formula: see text] in detail utilizing first-principles methods based on the density functional theory (DFT). Within the scope of both PBE and HSE06 including spin orbit coupling (SOC), the simulations predict the electronic band gap values to decrease as the number of layers increases. Moreover, spin-polarized DFT calculations combined with the semi-classical Boltzmann transport theory are applied to estimate the anisotropic thermoelectric power factor (Seebeck coefficient, S) for [Formula: see text] in both the monolayer and multilayer limit, and S is obtained below the optimal value for practical applications. The optical absorbance of [Formula: see text] monolayer is obtained to be slightly less than the values reported in literature for 2H TMD monolayers of [Formula: see text], [Formula: see text], and [Formula: see text]. Furthermore, we simulate the impact of defects, such as vacancy, antisite and substitution defects, on the electronic, optical and thermoelectric properties of monolayer [Formula: see text]. Particularly, the Te-[Formula: see text] substitution defect in parallel orientation yields negative formation energy, indicating that the relevant defect may form spontaneously under relevant experimental conditions. We reveal that the electronic band structure of [Formula: see text] monolayer is significantly influenced by the presence of the considered defects. According to the calculated band gap values, a lowering of the conduction band minimum gives rise to metallic characteristics to the structure for the single Te(1) vacancy, a diagonal Te line defect, and the Te(1)-[Formula: see text] substitution, while the other investigated defects cause an opening of a small positive band gap at the Fermi level. Consequently, the real ([Formula: see text]) and imaginary ([Formula: see text]) parts of the dielectric constant at low frequencies are very sensitive to the applied defects, whereas we find that the absorbance (A) at optical frequencies is less significantly affected. We also predict that certain point defects can enhance the otherwise moderate value of S in pristine [Formula: see text] to values relevant for thermoelectric applications. The described [Formula: see text] monolayers, as functionalized with the considered defects, offer the possibility to be applied in optical, electronic, and thermoelectric devices.
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Affiliation(s)
- Ilkay Ozdemir
- Physics Department, Adnan Menderes University, 09100 Aydin, Turkey
| | - Alexander W. Holleitner
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center of Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
| | - Christoph Kastl
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center of Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 Munich, Germany
| | - Olcay Üzengi Aktürk
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Electrical Electronics Engineering Department, Adnan Menderes University, 09100 Aydin, Turkey
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Ultrahigh transverse thermoelectric power factor in flexible Weyl semimetal WTe 2. Nat Commun 2022; 13:3909. [PMID: 35798731 PMCID: PMC9262886 DOI: 10.1038/s41467-022-31372-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/16/2022] [Indexed: 11/19/2022] Open
Abstract
Topological semimetals are well known for their interesting physical properties, while their mechanical properties have rarely received attention. With the increasing demand for flexible electronics, we explore the great potential of the van der Waals bonded Weyl semimetal WTe2 for flexible thermoelectric applications. We find that WTe2 single crystals have an ultrahigh Nernst power factor of ~3 Wm−1K−2, which outperforms the conventional Seebeck power factors of the state-of-the-art thermoelectric semiconductors by 2–3 orders of magnitude. A unique band structure that hosts compensated electrons and holes with extremely high mobilities is the primary mechanism for this huge Nernst power factor. Moreover, a large Ettingshausen signal of ~5 × 10−5 KA−1m is observed at 23.1 K and 9 T. In this work, the combination of the exceptional Nernst–Ettingshausen performance and excellent mechanical transformative ability of WTe2 would be instructive for flexible micro-/nano-thermoelectric devices. Flexible thermoelectrics are of great interest with increasing demand of flexible and wearable electronics. Here, the authors demonstrate that the Weyl semimetal, WTe2, has a high Nernst power factor and great mechanical flexibility.
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Ultrafast photothermoelectric effect in Dirac semimetallic Cd 3As 2 revealed by terahertz emission. Nat Commun 2022; 13:1623. [PMID: 35338125 PMCID: PMC8956572 DOI: 10.1038/s41467-022-29168-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/17/2022] [Indexed: 11/18/2022] Open
Abstract
The thermoelectric effects of topological semimetals have attracted tremendous research interest because many topological semimetals are excellent thermoelectric materials and thermoelectricity serves as one of their most important potential applications. In this work, we reveal the transient photothermoelectric response of Dirac semimetallic Cd3As2, namely the photo-Seebeck effect and photo-Nernst effect, by studying the terahertz (THz) emission from the transient photocurrent induced by these effects. Our excitation polarization and power dependence confirm that the observed THz emission is due to photothermoelectric effect instead of other nonlinear optical effect. Furthermore, when a weak magnetic field (~0.4 T) is applied, the response clearly indicates an order of magnitude enhancement on transient photothermoelectric current generation compared to the photo-Seebeck effect. Such enhancement supports an ambipolar transport nature of the photo-Nernst current generation in Cd3As2. These results highlight the enhancement of thermoelectric performance can be achieved in topological Dirac semimetals based on the Nernst effect, and our transient studies pave the way for thermoelectric devices applicable for high field circumstance when nonequilibrium state matters. The large THz emission due to highly efficient photothermoelectric conversion is comparable to conventional semiconductors through optical rectification and photo-Dember effect. Many topological semimetals are excellent thermoelectric materials, but previous studies were limited to steady-state properties. Here, the authors observe a transient thermoelectric response in Cd3As2 by detecting the resulting THz emission, with an enhanced response when a small magnetic field is applied.
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Kumar N, Guin SN, Manna K, Shekhar C, Felser C. Topological Quantum Materials from the Viewpoint of Chemistry. Chem Rev 2021; 121:2780-2815. [PMID: 33151662 PMCID: PMC7953380 DOI: 10.1021/acs.chemrev.0c00732] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Indexed: 11/29/2022]
Abstract
Topology, a mathematical concept, has recently become a popular and truly transdisciplinary topic encompassing condensed matter physics, solid state chemistry, and materials science. Since there is a direct connection between real space, namely atoms, valence electrons, bonds, and orbitals, and reciprocal space, namely bands and Fermi surfaces, via symmetry and topology, classifying topological materials within a single-particle picture is possible. Currently, most materials are classified as trivial insulators, semimetals, and metals or as topological insulators, Dirac and Weyl nodal-line semimetals, and topological metals. The key ingredients for topology are certain symmetries, the inert pair effect of the outer electrons leading to inversion of the conduction and valence bands, and spin-orbit coupling. This review presents the topological concepts related to solids from the viewpoint of a solid-state chemist, summarizes techniques for growing single crystals, and describes basic physical property measurement techniques to characterize topological materials beyond their structure and provide examples of such materials. Finally, a brief outlook on the impact of topology in other areas of chemistry is provided at the end of the article.
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Affiliation(s)
- Nitesh Kumar
- Max Planck Institute for
Chemical
Physics of Solids, 01187 Dresden, Germany
| | - Satya N. Guin
- Max Planck Institute for
Chemical
Physics of Solids, 01187 Dresden, Germany
| | - Kaustuv Manna
- Max Planck Institute for
Chemical
Physics of Solids, 01187 Dresden, Germany
| | - Chandra Shekhar
- Max Planck Institute for
Chemical
Physics of Solids, 01187 Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for
Chemical
Physics of Solids, 01187 Dresden, Germany
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8
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Nag T, Nandy S. Magneto-transport phenomena of type-I multi-Weyl semimetals in co-planar setups. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:075504. [PMID: 33080589 DOI: 10.1088/1361-648x/abc310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Having the chiral anomaly (CA) induced magneto-transport phenomena extensively studied in single Weyl semimetal as characterized by topological charge n = 1, we here address the transport properties in the context of multi-Weyl semimetals (m-WSMs) where n > 1. Using semiclassical Boltzmann transport formalism with the relaxation time approximation, we investigate several intriguing transport properties such as longitudinal magneto-conductivity (LMC), planar Hall conductivity (PHC), thermo-electric coefficients (TECs) and planar Nernst coefficient (PNC) for m-WSMs in the co-planar setups with external magnetic field, electric field and temperature gradient. Starting from the low-energy model, we show analytically that at zero temperature both LMC and PHC vary cubically with topological charge as n 3 while the finite temperature (T ≠ 0) correction is proportional to (n + n 2)T 2. Interestingly, we find that both the longitudinal and transverse TECs vary quadratically with topological charge as n 2 and the PNC is found to vary non-monotonically as a function of n. Our study hence clearly suggests that the inherent properties of m-WSMs indeed show up distinctly through the CA and the chiral magnetic effect induced transport coefficients in two different setups. Moreover, in order to obtain an experimentally realizable picture, we simultaneously verify our analytical findings through the numerical calculations using the lattice model of m-WSMs.
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Affiliation(s)
- Tanay Nag
- Max-Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - Snehasish Nandy
- Max-Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
- Department of Physics, Indian Institute of Technology Kharagpur, W.B. 721302, India
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9
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Menon A, Basu B. Anomalous Hall transport in tilted multi-Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:045602. [PMID: 32947280 DOI: 10.1088/1361-648x/abb9b8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
We study the effect of a perpendicular magnetic fieldBon a multinode Weyl semimetal (mWSM) of arbitrary integer monopole chargen, with the two Weyl multinodes separated ink-space. Besides type-I mWSMs, there exist type-II mWSMs which are characterized by the tilted minimal dispersion for low-energy excitations; the Weyl points in type-II mWSMs are still protected crossings but appear at the contact of the electron and hole pockets, after the Lifshitz transition. We find that the presence of a perpendicular magnetic field quantizes the occupation pockets due to the presence of Fermi tubes. In this theory, the Hilbert space is spanned by a set ofnchiral degenerate ground states, and a countably infinite number of particle-hole symmetric Landau levels (LLs). We calculate the Hall conductivity for the tilt-symmetric case of type-I mWSM using the Kubo formula, in the zero-frequency (DC) limit, and recover the well-known vacuum contribution. We compute the Fermi surface corrections and show that the expression generalizes from the formula for elementary (n= 1) type-I WSMs. We derive an expression for the type-II mWSM Hall conductivity, which is bounded by a LL cutoff introduced on physical grounds. Interestingly, we find that the anomalous vacuum Hall conductivity is vanishing in the type-II phase at all temperatures. The corresponding thermal Hall and Nernst conductivities are evaluated and characterized for both phases. The qualitative and quantitative observations presented here may serve in the characterization of generic mWSMs of both types.
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Affiliation(s)
- Anirudha Menon
- Department of Physics, University of California, Davis, California 95616, United States of America
| | - Banasri Basu
- Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108, India
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10
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Wang Y, Wang L, Liu X, Wu H, Wang P, Yan D, Cheng B, Shi Y, Watanabe K, Taniguchi T, Liang SJ, Miao F. Direct Evidence for Charge Compensation-Induced Large Magnetoresistance in Thin WTe 2. NANO LETTERS 2019; 19:3969-3975. [PMID: 31082263 DOI: 10.1021/acs.nanolett.9b01275] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Since the discovery of extremely large nonsaturating magnetoresistance (MR) in WTe2, much effort has been devoted to understanding the underlying mechanism, which is still under debate. Here, we explicitly identify the dominant physical origin of the large nonsaturating MR through in situ tuning of the magneto-transport properties in thin WTe2 film. With an electrostatic doping approach, we observed a nonmonotonic gate dependence of the MR. The MR reaches a maximum (10600%) in thin WTe2 film at certain gate voltage where electron and hole concentrations are balanced, indicating that the charge compensation is the dominant mechanism of the observed large MR. Besides, we show that the temperature-dependent magnetoresistance exhibits similar tendency with the carrier mobility when the charge compensation is retained, revealing that distinct scattering mechanisms may be at play for the temperature dependence of magneto-transport properties. Our work would be helpful for understanding mechanism of the large MR in other nonmagnetic materials and offers an avenue for achieving large MR in the nonmagnetic materials with electron-hole pockets.
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Affiliation(s)
- Yaojia Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Lizheng Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Xiaowei Liu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Heng Wu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Pengfei Wang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Dayu Yan
- Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Bin Cheng
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Youguo Shi
- Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Kenji Watanabe
- National Institute for Materials Science , 1-1 Namiki Tsukuba , Ibaraki 305-0044 , Japan
| | - Takashi Taniguchi
- National Institute for Materials Science , 1-1 Namiki Tsukuba , Ibaraki 305-0044 , Japan
| | - Shi-Jun Liang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Feng Miao
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
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11
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Wang Q, Yesilyurt C, Liu F, Siu ZB, Cai K, Kumar D, Liu Z, Jalil MBA, Yang H. Anomalous Photothermoelectric Transport Due to Anisotropic Energy Dispersion in WTe 2. NANO LETTERS 2019; 19:2647-2652. [PMID: 30859825 DOI: 10.1021/acs.nanolett.9b00513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Band structures are vital in determining the electronic properties of materials. Recently, the two-dimensional (2D) semimetallic transition metal tellurides (WTe2 and MoTe2) have sparked broad research interest because of their elliptical or open Fermi surface, making distinct from the conventional 2D materials. In this study, we demonstrate a centrosymmetric photothermoelectric voltage distribution in WTe2 nanoflakes, which has not been observed in common 2D materials such as graphene and MoS2. Our theoretical model shows the anomalous photothermoelectric effect arises from an anisotropic energy dispersion and micrometer-scale hot carrier diffusion length of WTe2. Further, our results are more consistent with the anisotropic tilt direction of energy dispersion being aligned to the b-axis rather than the a-axis of the WTe2 crystal, which is consistent with the previous first-principle calculations as well as magneto-transport experiments. Our work shows the photothermoelectric current is strongly confined to the anisotropic direction of the energy dispersion in WTe2, which opens an avenue for interesting electro-optic applications such as electron beam collimation and electron lenses.
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Affiliation(s)
- Qisheng Wang
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
| | - Can Yesilyurt
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
| | - Fucai Liu
- Center for Programmable Materials, School of Electrical and Electronic Engineering , Nanyang Technology University , 639798 , Singapore
| | - Zhuo Bin Siu
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
| | - Kaiming Cai
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
| | - Dushyant Kumar
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
| | - Zheng Liu
- Center for Programmable Materials, School of Electrical and Electronic Engineering , Nanyang Technology University , 639798 , Singapore
| | - Mansoor B A Jalil
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering , National University of Singapore , 117576 , Singapore
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