Pressure-induced enhancement of superconductivity and suppression of semiconducting behavior in Ln(O0.5F0.5)BiS2 (Ln = La, Ce) compounds

TL;DR

This study investigates how applying pressure enhances superconductivity and suppresses semiconducting behavior in Ln(O0.5F0.5)BiS2 compounds, revealing reversible changes and optimal Tc at specific pressures.

Contribution

It provides new insights into pressure effects on superconductivity and semiconducting properties in LnBiS2 compounds, identifying maximum Tc values and reversible phase transitions.

Findings

Superconducting Tc increases with pressure up to a maximum and then decreases.

Semiconducting behavior is suppressed under pressure, reversible upon pressure release.

Transient broadening of the superconducting transition occurs between low and high Tc phases.

Abstract

Electrical resistivity measurements as a function of temperature between 1 K and 300 K were performed at various pressures up to 3 GPa on the superconducting layered compounds Ln(O0.5F0.5)BiS2 (Ln = La, Ce). At atmospheric pressure, La(O0.5F0.5)BiS2 and Ce(O0.5F0.5)BiS2 have superconducting critical temperatures, Tc, of 3.3 K and 2.3 K, respectively. For both compounds, the superconducting critical temperature Tc initially increases, reaches a maximum value of 10.1 K for La(O0.5F0.5)BiS2 and 6.7 K for CeO(0.5F0.5)BiS2, and then gradually decreases with increasing pressure. Both samples also exhibit transient behavior in the region between the lower Tc phase near atmospheric pressure and the higher Tc phase. This region is characterized by a broadening of the superconducting transition, in which Tc and the transition width, delta Tc, are reversible with increasing and decreasing pressure. There is also an appreciable pressure-induced and hysteretic suppression of semiconducting behavior up to the pressure at which the maximum value of Tc is found. At pressures above the value at which the maximum in Tc occurs, there is a gradual decrease of Tc and further suppression of the semiconducting behavior with pressure, both of which are reversible.