Interplay of Superconductivity, Antiferromagnetism, and Pauli Depairing in CeCoIn5
Abstract
Low temperature magnetization M measurements down to 70~mK have been performed through the superconducting upper critical field Hc2 of CeCoIn5 with the field H parallel to the c axis of the tetragonal crystal. The crossing through the upper critical field Hc2(0) is marked by a sign change in the temperature dependence of M(T). A Fermi liquid law of the magnetization is observed in the superconducting phase while in the paramagnetic state above Hc2 a quasi-linear temperature dependence is obeyed. The specific heat below Hc2 is therefor dominated by the increase of γ (H), the linear term of the specific heat, and is marked by a singularity at Hc2 (0). No indication of the so called Q-phase was observed below Hc2 (in contrast to the case with H applied in the basal plane).