In-plane and out-of-plane superfluid density of the layered organic superconductor κ-(BEDT-TTF)_2Cu[N(CN)_2]Br

摘要

The anisotropic magnetic penetration depth λ_b(t) and λ_(ac)(t), where t = T/T_c, in the layered organic superconductor κ-(BEDT-TTF)_2Cu[N(CN)_2]Br (abbreviated as κ-ET-Br) are obtained from AC susceptibility data. We find λ_b(0) = 133 μm, consistent with earlier results and Δλ_b(t) = λ_b(t) - λ_b(0) ∝ t~2, which is new. Also, assuming λ_(ac)(0) ≈ 1 μm, we obtain Δλ_(ac)(t) ∝ t. The observed power laws are consistent with the ones expected in d-wave superconductivity.