Superconductivity in non-centrosymmetric sulfide Y_xS₄

¹ Materials Research Center for Element Strategy, Tokyo Institute of Technology - 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
² Laboratory for Materials and Structures, Tokyo Institute of Technology - 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan

^(a) Present address: School of Physical Science and Technology, ShanghaiTech University - Shanghai, China; qiyp@shanghaitech.edu.cn
^(b) hosono@msl.titech.ac.jp

Received: 23 December 2017
Accepted: 26 March 2018

Abstract

We report the synthesis and characterization of the non-centrosymmetric superconductor Y_xS₄ (x = 2.69, 2.75, 2.86, 2.96) using powder x-ray diffraction (XRD), magnetization, and transport measurements. It crystallized in a non-centrosymmetric Th₃P₄-type structure (space group , Z = 4). Resistivity and DC magnetization measurements confirmed that Y_2.96S₄ has type-II superconductivity with the transition temperature , lower critical field , and upper critical field . The experimental and density functional calculation results suggest that Y_xS₄ could be categorized as a Bardeen-Cooper-Schrieffer (BCS) superconductor with intermediate coupling.