Extended Magnetic Dome Induced by Low Pressures in Superconducting FeSe1-x Sx

Abstract

We report muon spin rotation and magnetization measurements under pressure on Fe1+δSe1-xSx with x≈0.11. Above p≈0.6 GPa we find a microscopic coexistence of superconductivity with an extended dome of long range magnetic order that spans a pressure range between previously reported separated magnetic phases. The magnetism initially competes on an atomic scale with the coexisting superconductivity leading to a local maximum and minimum of the superconducting Tc(p). The maximum of Tc corresponds to the onset of magnetism while the minimum coincides with the pressure of strongest competition. A shift of the maximum of Tc(p) for a series of single crystals with x up to 0.14 roughly extrapolates to a putative magnetic and superconducting state at ambient pressure for x≥0.2. © 2019 American Physical Society.