Angular dependent torque measurements on CaFe0.88Co0.12AsF

Abstract

Out-of-plane angular dependent torque measurements were performed on CaFe0.88Co0.12AsF (Ca1 1 1 1) single crystals. In the normal state, the torque data shows angular dependence and H2 magnetic field dependence, as a result of paramagnetism. In the mixed state, the torque signal is a combination of the vortex torque and paramagnetic torque, and the former allows the determination of the anisotropy parameter γ. At T = 11.5 K, γ (11.5 K ≃ 0.5 Tc) = 19.1, which is similar to the result of SmFeAsO0.8F0.2, at . So the 11 1 1 is more anisotropic compared to 11 and 122 families of iron-based superconductors. This may suggest that the electronic coupling between layers in 1 1 1 1 is less effective than in 11 and 122 families.