Pressure Induced Static Magnetic Order in Superconducting FeSe_1-x

TL;DR

This study explores how applying pressure to FeSe_1-x induces static magnetic order that coexists and competes with superconductivity, revealing complex phase behavior and enhanced transition temperatures.

Contribution

It provides detailed experimental evidence of pressure-induced static magnetic order coexisting with superconductivity in FeSe_1-x, expanding understanding of its phase diagram.

Findings

Static magnetic order appears above T_c at ~0.8 GPa

Coexistence and competition of magnetism and superconductivity observed

Both magnetic and superconducting transition temperatures increase with pressure

Abstract

We report on a detailed investigation of the electronic phase diagram of FeSe_1-x under pressures up to 1.4GPa by means of AC magnetization and muon-spin rotation. At a pressure \simeq0.8GPa the non-magnetic and superconducting FeSe_1-x enters a region where long range static magnetic order is realized above T_c and bulk superconductivity coexists and competes on short length scales with the magnetic order below T_c. For even higher pressures an enhancement of both the magnetic and the superconducting transition temperatures as well as of the corresponding order parameters is observed. These exceptional properties make FeSe1-x to be one of the most interesting superconducting systems investigated extensively at present.