English

Bulk Fermi-surface of the Weyl type-II semi-metallic candidate MoTe2

Mesoscale and Nanoscale Physics 2017-10-24 v5 Superconductivity

Abstract

The electronic structure of WTe2_2 and orthorhombic γ\gamma-MoTe2_2, are claimed to contain pairs of Weyl type-II points. A series of ARPES experiments claim a broad agreement with these predictions. We synthesized single-crystals of MoTe2_2 through a Te flux method to validate these predictions through measurements of its bulk Fermi surface (FS) \emph{via} quantum oscillatory phenomena. We find that the superconducting transition temperature of γ\gamma-MoTe2_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 WTe2_2, the magnetoresistivity of γ\gamma-MoTe2_2 does not saturate at high magnetic fields and can easily surpass 10610^{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 εF\varepsilon_F. Here, we show that a shift of the DFT valence bands relative to εF\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 γ\gamma-MoTe2_2.

Keywords

Cite

@article{arxiv.1605.09065,
  title  = {Bulk Fermi-surface of the Weyl type-II semi-metallic candidate MoTe2},
  author = {D. Rhodes and R. Schönemann and N. Aryal and Q. Zhou and Q. R. Zhang and E. Kampert and Y. -C. Chiu and Y. Lai and Y. Shimura and G. T. McCandless and J. Y. Chan and D. W. Paley and J. Lee and A. D. Finke and J. P. C. Ruff and S. Das and E. Manousakis and L. Balicas},
  journal= {arXiv preprint arXiv:1605.09065},
  year   = {2017}
}

Comments

13 pages, 7 figures, supplementary file not included (in press)