Fermi surfaces and orbital polarization in superconducting CeO$_{0.5}$F$_{0.5}$BiS$_{2}$ revealed by angle-resolved photoemission spectroscopy

TL;DR

This study uses ARPES to reveal the orbital composition and quasi-one-dimensional electronic structure of the Fermi surfaces in the superconducting CeO$_{0.5}$F$_{0.5}$BiS$_{2}$, highlighting orbital polarization and potential Jahn-Teller distortions.

Contribution

First detailed ARPES analysis of orbital characters and Fermi surface topology in CeO$_{0.5}$F$_{0.5}$BiS$_{2}$, revealing orbital polarization and electronic anisotropy.

Findings

Fermi pockets around X are dominated by Bi 6p_x orbitals.

Orbital polarization suggests quasi-one-dimensional electronic structure.

Distortions may induce band Jahn-Teller effects.

Abstract

We have investigated the electronic structure of BiS$_2$-based CeO$_{0.5}$F$_{0.5}$BiS$_2$ superconductor using polarization-dependent angle-resolved photoemission spectroscopy (ARPES), and succeeded in elucidating the orbital characters on the Fermi surfaces. In the rectangular Fermi pockets around X point, the straight portion parallel to the $k_y$ direction is dominated by Bi $6p_x$ character. The orbital polarization indicates the underlying quasi-one-dimensional electronic structure of the BiS$_2$ system. Moreover, distortions on tetragonally aligned Bi could give rise to the band Jahn-Teller effect.