Structural-transition-induced quasi two-dimensional Fermi surface in FeSe

Abstract

We report detailed study of angular-dependent magnetoresistance (AMR) with tilting angel $\hat{I}¸$ from $c$-axis ranging from 0${}^{\circ }$ to 360${}^{\circ }$ on a high-quality FeSe single crystal. A pronounced AMR with twofold symmetry is observed, which is caused by the quasi two-dimensional (2D) Fermi surface. The pronounced AMR is observed only in the orthorhombic phase, indicating that the quasi-2D Fermi surface is induced by the structural transition. Details about the influence of the multiband effect to the AMR are also discussed. Besides, the angular response of a possible Dirac-cone-like band structure is investigated by analyzing the detailed magnetoresistance at different $\hat{I}¸$. The obtained characteristic field ($B^{\ast }$) can be also roughly scaled in the 2D approximation, which indicates that the Dirac-cone-like state is also 2D in nature.

7 pages, 5 figures