Nanoscale-phase-separation–enhanced critical current and vortex transition temperature in K_0.62Fe_1.71Se₂ crystals

¹ Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China - Hefei 230026, PRC
² Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Science Hefei 230026, PRC
³ Collaborative Innovation Center of Advanced Microstructures, Nanjing University - Nanjing 210093, PRC

^(a) lixg@ustc.edu.cn

Received: 11 April 2015
Accepted: 22 July 2015

Abstract

The critical current and vortex glass (VG) transition of K_0.62Fe_1.71Se₂ crystal have been studied via measuring the current-voltage characteristics by rotating the crystal around its c-axis in magnetic fields parallel to the ab-plane. It is found that the curves show a good three-dimensional VG scaling collapse. The and VG transition temperature exhibit a distinct fourfold symmetry due to the in-plane fourfold superconducting stripe structure in the nanoscale phase-separated system. The is clearly enhanced for fields parallel to the superconducting stripe owning to the increased pinning associated with the nanoscale phase separation.