Title: Bulk Fermi surface of the Weyl type-II semimetallic candidate $\gamma -{\mathrm{MoTe}}_2$

Abstract

The electronic structure of semi-metallic transition-metal dichalcogenides, such as WTe$$_2$$ and orthorhombic $$\gamma-$$MoTe$$_2$$, are claimed to contain pairs of Weyl points or linearly touching electron and hole pockets associated with a non-trivial Chern number. For this reason, these compounds were recently claimed to conform to a new class, deemed type-II, of Weyl semi-metallic systems. A series of angle resolved photoemission experiments (ARPES) claim a broad agreement with these predictions detecting, for example, topological Fermi arcs at the surface of these crystals. We synthesized single-crystals of semi-metallic MoTe$$_2$$ through a Te flux method to validate these predictions through measurements of its bulk Fermi surface (FS) via quantum oscillatory phenomena. We find that the superconducting transition temperature of $$\gamma-$$MoTe$$_2$$ depends on disorder as quantified by the ratio between the room- and low-temperature resistivities, suggesting the possibility of an unconventional superconducting pairing symmetry. Similarly to WTe$$_2$$, the magnetoresistivity of $$\gamma-$$MoTe$$_2$$ does not saturate at high magnetic fields and can easily surpass $$10^{6}$$ \%. Remarkably, the analysis of the de Haas-van Alphen (dHvA) signal superimposed onto the magnetic torque, indicates that the geometry of its FS is markedly distinct from the calculated one. The dHvA signal also reveals that the FS is affected by the Zeeman-effect precluding the extraction of the Berry-phase. A direct comparison between the previous ARPES studies and density-functional-theory (DFT) calculations reveals a disagreement in the position of the valence bands relative to the Fermi level $$\varepsilon_F$$. Here in this paper, we show that a shift of the DFT valence bands relative to $$\varepsilon_F$$, in order to match the ARPES observations, and of the DFT electron bands to explain some of the observed dHvA frequencies, leads to a good agreement between the calculations and the angular dependence of the FS cross-sectional areas observed experimentally. However, this relative displacement between electron- and hole-bands eliminates their crossings and, therefore, the Weyl type-II points predicted for $$\gamma-$$MoTe$$_2$$

Authors:

Rhodes, D. ^[1]; Schönemann, R. ^[2]; Aryal, N. ^[1]; Zhou, Q. ^[1]; Zhang, Q. R. ^[1]; Kampert, E. ^[3]; Chiu, Y. -C. ^[1]; Lai, Y. ^[1]; Shimura, Y. ^[4]; McCandless, G. T. ^[5]; Chan, J. Y. ^[5]; Paley, D. W. ^[6]; Lee, J. ^[7]; Finke, A. D. ^[7]; Ruff, J. P. C. ^[7]; Das, S. ^[1]; Manousakis, E. ^[1]; Balicas, L. ^[1]

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+ Show Author Affiliations

1. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Florida State Univ., Tallahassee, FL (United States). Dept. of Physics
2. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
3. Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Dresden High Magnetic Field Lab. (HLD-EMFL)
4. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Univ. of Tokyo (Japan). Inst. of Solid State Physics
5. Univ. of Texas at Dallas, Richardson, TX (United States). Dept. of Chemistry and Biochemistry
6. Columbia Univ., New York, NY (United States). Dept. of Chemistry, Columbia Nano Initiative
7. Cornell Univ., Ithaca, NY (United States). Cornell High Energy Synchrotron Source (CHESS)

Publication Date:

2017-10-17

Research Org.:

National High Magnetic Field Lab - Florida State University

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1399695

Alternate Identifier(s):

OSTI ID: 1399806

Grant/Contract Number:  

SC0002613; DMR-1360863; W911NF-11-1-0362; DMR-1332208; DMR-1157490

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 96; Journal Issue: 16; Related Information: https://journals.aps.org/prb/supplemental/10.1103/PhysRevB.96.165134; 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; Weyl semi-metals; superconductivity; magnetoresistivity; Hall-effect; band structure calculations