Two-band and pauli-limiting effects on the upper critical field of 112-type iron pnictide superconductors

Xiangzhuo Xing; Wei Zhou; Jinhua Wang; Zengwei Zhu; Yufeng Zhang; Nan Zhou; Bin Qian; Xiaofeng Xu; Zhixiang Shi

doi:10.1038/srep45943

Two-band and pauli-limiting effects on the upper critical field of 112-type iron pnictide superconductors

Sci Rep. 2017 Apr 6:7:45943. doi: 10.1038/srep45943.

Authors

Xiangzhuo Xing¹, Wei Zhou¹, Jinhua Wang², Zengwei Zhu², Yufeng Zhang¹, Nan Zhou¹, Bin Qian³, Xiaofeng Xu³, Zhixiang Shi¹

Affiliations

¹ Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
² Wuhan National High Magnetic Field Center, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China.
³ Advanced Functional Materials Lab and Department of Physics, Changshu Institute of Technology, Changshu 215500, China.

Abstract

The temperature dependence of upper critical field μ₀H_c2 of Ca_0.83La_0.17FeAs₂ and Ca_0.8La_0.2Fe_0.98Co_0.02As₂ single crystals are investigated by measuring the resistivity for the inter-plane (H//c) and in-plane (H//ab) directions in magnetic fields up to 60 T. It is found that μ₀H_c2(T) of both crystals for H//c presents a sublinear temperature dependence with decreasing temperature, whereas the curve of μ₀H_c2(T) for H//ab has a convex curvature and gradually tends to saturate at low temperatures. μ₀H_c2(T) in both crystals deviates from the conventional Werthamer-Helfand-Hohenberg (WHH) theoretical model without considering spin paramagnetic effect for H//c and H//ab directions. Detailed analyses show that the behavior of μ₀H_c2(T) in 112-type Iron-based superconductors (IBSs) is similar to that of most IBSs. Two-band model is required to fully reproduce the behavior of μ₀H_c2(T) for H//c, while the effect of spin paramagnetic effect is responsible for the behavior of μ₀H_c2(T) for H//ab.

Publication types

Research Support, Non-U.S. Gov't