Superconductivity in non-centrosymmetric sulfide YxS4 Yanpeng Qi, Zewen Xiao, Jiangang Guo, Hechang Lei, Toshio Kamiya and Hideo Hosono EPL, 121 5 (2018) 57001 Published online: 09 May 2018 DOI: 10.1209/0295-5075/121/57001