Superconductivity and normal state magnetoresistance in superconducting FeSe:Sb

Abstract

We prepared a series of β-FeSe samples with a nominal composition of Fe1.11Se1−x Sb x (0⩽x⩽0.5). The X-ray diffraction, transport and magnetic measurements were performed on these samples to investigate the structure, the superconducting properties and the normal state transport and magnetic properties. Although the X-ray diffraction data suggested that Sb atoms were not incorporated into the β-FeSe phase, the transport data showed observable changes of superconductivity, normal state resistivity and magnetoresistance. This was represented by the increase in the superconducting transition temperature and the upper critical field. Also, for the samples with a low level of Sb content, a clear decrease of the normal state resistivity and a substantial increase of the residual resistance ratio were observed. Furthermore, the samples showed a significant increase of the normal state magnetoresistance that appeared not to follow the Kohler’s rule. The results were discussed in the frame of reduction of excess Fe at interstitial sites of β-FeSe.