Anomalous impact of hydrostatic pressure on superconductivity of polycrystalline LaO0.5F0.5BiSe2

TL;DR

This study discovers that applying hydrostatic pressure to LaO0.5F0.5BiSe2 initially suppresses its superconductivity, but beyond a certain pressure, a higher Tc phase emerges, indicating an anomalous pressure effect.

Contribution

It reveals an unusual pressure dependence of superconductivity in LaO0.5F0.5BiSe2, including the emergence of a higher Tc phase at elevated pressures.

Findings

Superconductivity at 2.5K in LaO0.5F0.5BiSe2 confirmed by susceptibility and resistivity.

Superconducting Tc decreases with pressure up to 1.68 GPa.

A higher Tc phase (>5K) appears above 2.5 GPa.

Abstract

We report bulk superconductivity at 2.5K in LaO0.5F0.5BiSe2 compound through the DC magnetic susceptibility and electrical resistivity measurements. The synthesized LaO0.5F0.5BiSe2 compound is crystallized in tetragonal structure with space group P4/nmm and Reitveld refined lattice parameters are a= 4.15(1)A and c=14.02(2)A. The lower critical field of Hc1= 40Oe, at temperature 2K is estimated through the low field magnetization measurements. The LaO0.5F0.5BiSe2 compound showed metallic normal state electrical resistivity with residual resistivity value of 1.35m{\Omega}-cm. The compound is type-II superconductor, and the estimated Hc2(0) value obtained by WHH formula is above 20kOe for 90percent Rn criteria. The superconducting transition temperature decreases with applied pressure till around 1.68GPa and with further higher pressures a high Tc phase emerges with possible onset Tc of above 5K for 2.5GPa.