Observation of anomalous temperature dependence of spectrum on small Fermi surfaces in a BiS2-based superconductor

Abstract

We have performed an angle-resolved photoemission spectroscopy study of the BiS2-based superconductor Nd(O,F)BiS2. Two small electronlike Fermi surfaces around X(π,0) are observed, which enclose 2.4% and 1.1% of the Brillouin zone area, respectively, corresponding to an electron doping of 7% per Bi site. The Fermi surface topology is far from the nesting scenario proposed in most of the theoretical models for the BiS2-based superconductors. The conduction bands show significant anisotropic splitting along XM and ΓX, which is attributed to the cooperative effects of large spin-orbit coupling and interlayer coupling. The low-energy spectrum exhibits a weakly dispersing broad hump near the bottom of the conduction bands. This hump is drastically suppressed with increasing temperature, while the spectral weight at the Fermi level is essentially unaffected. These anomalous spectral features indicate that the electrons could be strongly coupled with the lattice in the low-temperature normal state of this superconductor.

Source-reported materials — not catalogue approval

Similar papers