Bulk Fermi surface of the layered superconductor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>TaS</mml:mi><mml:msub><mml:mi mathvariant="normal">e</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> with three-dimensional strong topological state
Wei Xia, Xianbiao Shi, Yong Zhang, Hao Su, Qin Wang, Linchao Ding, Leiming Chen, Xia Wang, Zhiqiang Zou, Na Yu, Li Pi, Yufeng Hao, Bin Li, Zengwei Zhu, Weiwei Zhao, Xufeng Kou, Yanfeng Guo
Abstract
High-magnetic-field transport measurements and ab initio calculations on the layered superconductor $\mathrm{TaS}{\mathrm{e}}_{3}$ have provided evidence for the existence of a three-dimensional strong topological state. Longitudinal magnetotransport measurements up to \ensuremath{\sim}33 T unveiled striking Shubnikov--de Haas oscillations with two fundamental frequencies at 100 and 175 T corresponding to a nontrivial hole Fermi pocket at the \ensuremath{\Gamma} point and a nontrivial electron Fermi pocket at the B point, respectively, in the Brillouin zone. However, calculations revealed one more electron pocket at the B point which was not detected by the magnetotransport measurements, presumably due to the limited carrier momentum relaxation time. Angle-dependent quantum oscillations by rotating the sample with respect to the magnetic field revealed clear changes in the two fundamental frequencies, indicating anisotropic electronic Fermi pockets. The ab initio calculations gave the topological ${Z}_{2}$ invariant of (1; 100) and revealed a single Dirac cone on the $(1\phantom{\rule{0.28em}{0ex}}0\phantom{\rule{0.28em}{0ex}}\ensuremath{-}1)$ surface at the $\overline{\mathrm{X}}$ point with helical spin texture at a constant energy contour, suggesting a strong topological state. The results demonstrate $\mathrm{TaS}{\mathrm{e}}_{3}$ as an excellent platform to study the interplay between the topological phase and superconductivity and a promising system for the exploration of topological superconductivity.