Correlation between superconductivity and antiferromagnetism in   Rb0.8Fe2Se2-xTex single crystals
  We report the first experimental evidence for the intimate connection between superconductivity and antiferromagnetism in Rb0.8Fe2Se2-xTex single crystal under negative chemical pressure by substituting Se with isovalent Te atoms. Electrical resistance measurements in the temperature range from 4 K to 550 K demonstrate that both superconducting transition temperature (Tc) and Neel temperature (TN) were suppressed continuously with the lattice expansion. When the Te concentration x in Rb0.8Fe2Se2-xTex approaches 0.3, the superconducting transition temperature Tc is completely suppressed and the sample behaves like a semiconductor, meanwhile the characteristic peak of antiferromagnetic transition on resistance curve disappears. Our observation suggests that the pressure-induced lattice expansion can be used to tune the correlativity of superconductivity and antiferromagnetism. 
Dachun Gu, Liling Sun, Qi Wu, Chao Zhang, Jing Guo, Peiwen Gao, Yue   Wu, Xiaoli Dong, Xi Dai and Zhongxian Zhao
cond-mat.supr-con