Pressure effect on superconductivity and magnetism in FeSex

TL;DR

This study investigates how applying pressure influences superconductivity and magnetism in FeSe_x, revealing coexistence of magnetic phases and superconductivity, with pressure enhancing transition temperatures and magnetic anomalies.

Contribution

It provides new insights into the pressure-induced enhancement of superconductivity and magnetic phase transitions in FeSe_x, demonstrating coexistence of magnetism and superconductivity.

Findings

Pressure raises Tc, Ts1, and Ts2 in FeSe_x.

Magnetic anomalies relate to ferromagnetic and antiferromagnetic transitions.

Superconductivity coexists with magnetic phases under pressure.

Abstract

In this paper, pressure effect on superconductivity and magnetism has been investigated in FeSex (x = 0.80, 0.88). The magnetization curves display anomaly at Ts1 106 K and Ts2 78 K except for the superconducting diamagnetic transition around Tc 8 K. The magnetic anomaly at Ts1 and Ts2 can be related to a ferromagnetic and an antiferromagnetic phase transition, respectively, as revealed by specific heat measurements. The application of pressure not only raises Tc, but also increases both Ts1 and Ts2. This system shows clear evidence that superconductivity arises in a phase with strong magnetic character and the superconductivity coexists with magnetism. In addition, the specific heat anomaly associated with the superconducting transition seems to be absent.