Effects of Cr doping on the superconductivity and magnetism of FeTe_(0.8)S_(0.2)

Abstract

We investigate the effects of Cr doping on the superconductivity and magnetism of layered compound FeTe_(0.8)S_(0.2), and find evidences for coexistence of ferromagnetism and superconductivity in the Cr-doped system. X-ray diffraction (XRD) spectra suggest that Cr dopants in Fe_(1-x)Cr_xTe_(0.8)S_(0.2) for x = 0.02, 0.04 and 0.06 primarily enter the sites in-between the FeTe_(1-y)S_y (0 < y ≤ 0.2) layers. Magnetic measurements reveal that the interlayer Cr dopants establish long-range ferromagnetic order with a doping dependent Curie temperature. On the other hand, the onset of superconductivity remains largely unaffected by the Cr-doping, although the superconducting transition width increases with increasing Cr doping while the superconducting diamagnetism decreases. Our observation suggests the compatibility of interlayer ferromagnetism with superconductivity in layered Fe_(1-x)Cr_xTe_(0.8)S_(0.2) compounds, similar to previous findings in other layer superconductors such as the cuprates and BiS₂-based compounds.