Superconductivity and abnormal pressure effect in Sr0.5La0.5FBiSe2 superconductor

TL;DR

This study reports the synthesis of a new Sr0.5La0.5FBiSe2 superconductor with a Tc of 3.8 K, revealing unique pressure-dependent electronic behaviors and suggesting a different electronic structure compared to similar compounds.

Contribution

The paper introduces a new BiSe2-based superconductor with distinct pressure effects and metallic behavior, expanding understanding of BiS2-based superconductors.

Findings

Superconducting transition temperature Tc is approximately 3.8 K.

The compound exhibits metallic behavior down to Tc, unlike other BiS2-based superconductors.

Pressure influences Tc, resistivity, and electronic behavior, indicating a different electronic structure.

Abstract

Through the solid state reaction method, we synthesized a new BiSe2-based superconductor Sr0:5La0:5FBiSe2 with superconducting transition temperature Tc?3.8 K. A strong diamagnetic signal below Tc in susceptibility ?(T) is observed indicating the bulk nature of superconductivity. Different to most BiS2-based compounds where superconductivity develops from a semiconducting-like normal state, the present compound exhibits a metallic behavior down to Tc. Under weak magnetic field or pressure, however, a remarkable crossover from metallic to insulating behaviors takes place around Tmin where the resistivity picks up a local minimum. With increasing pressure, Tc decreases monotonously and Tmin shifts to high temperatures, while the absolute value of the normal state resistivity at low temperatures first decreases and then increases with pressure up to 2.5 GPa. These results imply that the electronic structure of Sr0:5La0:5FBiSe2 may be different to those in the other BiS2-based systems.