Multiband character of β-FeSe: Angular dependence of The magnetoresistance and upper critical field

Abstract

We studied ab-plane transport properties in single crystals of The superconductor β-FeSe up to 16 T. In The normal state, below 90 K, The crystals present a strongly anisotropic positive magnetoresistance that becomes negligible above that temperature. In The superconducting state (Tc=8.87(5) K) The upper critical field anisotropy Hc2||ab/Hc2||c changes with temperature and The angular dependence of The dissipation for fixed temperatures and fields reflects a strongly anisotropic behavior. Our results make evident that multiband effects are needed to describe The measured transport properties. We model The magnetoresistance and upper critical field behavior with a two-band model showing that The diffusivities ratio parameter remains unchanged going from The normal to The superconducting state.