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

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.

SUBMITTER: Xing X 

PROVIDER: S-EPMC5382916 | biostudies-literature |

REPOSITORIES: biostudies-literature