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Title: Anisotropic electrodynamics of type-II Weyl semimetal candidate WTe 2

Abstract

We investigated the ab-plane optical properties of single crystals of WTe 2 for light polarized parallel and perpendicular to the W-chain axis over a broad range of frequency and temperature. At far-infrared frequencies, we observed a striking dependence of the reflectance edge on light polarization, corresponding to anisotropy of the carrier effective masses. We quantitatively studied the temperature dependence of the plasma frequency, revealing a modest increase of the effective mass anisotropy in the ab plane upon cooling. We also found strongly anisotropic interband transitions persisting to high photon energies. These results were analyzed by comparison with ab initio calculations. The calculated and measured plasma frequencies agree to within 10% for both polarizations, while the calculated interband conductivity shows excellent agreement with experiment.

Authors:
 [1];  [2];  [3];  [4];  [1];  [1];  [3];  [4]
  1. Univ. of California, San Diego, CA (United States). Dept. of Physics
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Condensed Matter Physics and Materials Science
  3. Princeton Univ., NJ (United States). Dept. of Chemistry
  4. Univ. of California, San Diego, CA (United States). Dept. of Physics; Columbia Univ., New York, NY (United States). Dept. of Physics
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Gordon and Betty Moore Foundation
OSTI Identifier:
1376187
Report Number(s):
BNL-114173-2017-JA
Journal ID: ISSN 2469-9950; PRBMDO; R&D Project: PO016; KC0202020; TRN: US1702802
Grant/Contract Number:
SC0012704; DMR1420541; DMR1609096
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 24; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Frenzel, A. J., Homes, C. C., Gibson, Q. D., Shao, Y. M., Post, K. W., Charnukha, A., Cava, R. J., and Basov, D. N. Anisotropic electrodynamics of type-II Weyl semimetal candidate WTe2. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.95.245140.
Frenzel, A. J., Homes, C. C., Gibson, Q. D., Shao, Y. M., Post, K. W., Charnukha, A., Cava, R. J., & Basov, D. N. Anisotropic electrodynamics of type-II Weyl semimetal candidate WTe2. United States. doi:10.1103/PhysRevB.95.245140.
Frenzel, A. J., Homes, C. C., Gibson, Q. D., Shao, Y. M., Post, K. W., Charnukha, A., Cava, R. J., and Basov, D. N. 2017. "Anisotropic electrodynamics of type-II Weyl semimetal candidate WTe2". United States. doi:10.1103/PhysRevB.95.245140.
@article{osti_1376187,
title = {Anisotropic electrodynamics of type-II Weyl semimetal candidate WTe2},
author = {Frenzel, A. J. and Homes, C. C. and Gibson, Q. D. and Shao, Y. M. and Post, K. W. and Charnukha, A. and Cava, R. J. and Basov, D. N.},
abstractNote = {We investigated the ab-plane optical properties of single crystals of WTe2 for light polarized parallel and perpendicular to the W-chain axis over a broad range of frequency and temperature. At far-infrared frequencies, we observed a striking dependence of the reflectance edge on light polarization, corresponding to anisotropy of the carrier effective masses. We quantitatively studied the temperature dependence of the plasma frequency, revealing a modest increase of the effective mass anisotropy in the ab plane upon cooling. We also found strongly anisotropic interband transitions persisting to high photon energies. These results were analyzed by comparison with ab initio calculations. The calculated and measured plasma frequencies agree to within 10% for both polarizations, while the calculated interband conductivity shows excellent agreement with experiment.},
doi = {10.1103/PhysRevB.95.245140},
journal = {Physical Review B},
number = 24,
volume = 95,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
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  • Cited by 25
  • It has recently been proposed that electronic band structures in crystals can give rise to a previously overlooked type of Weyl fermion, which violates Lorentz invariance and, consequently, is forbidden in particle physics. It was further predicted that Mo x W 1 - x Te 2 may realize such a type-II Weyl fermion. Here, we first show theoretically that it is crucial to access the band structure above the Fermi level ε F to show a Weyl semimetal in Mo x W 1 - x Te 2 . Then, we study Mo x W 1 - x Te 2 bymore » pump-probe ARPES and we directly access the band structure > 0.2 eV above ε F in experiment. By comparing our results with ab initio calculations, we conclude that we directly observe the surface state containing the topological Fermi arc. We propose that a future study of Mo x W 1 - x Te 2 by pump-probe ARPES may directly pinpoint the Fermi arc. Our work sets the stage for the experimental discovery of the first type-II Weyl semimetal in Mo x W 1 - x Te 2 .« less
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