We report specific heat measurements of the heavy fermion superconductor CeCoIn5 in the vicinity of the superconducting critical field H_{c2}, with magnetic field in the [110], [100], and [001] directions, and at temperatures down to 50 mK. The superconducting phase transition changes from second to first order for field above 10 T for H || [110] and H || [100]. In the same range of magnetic field we observe a second specific heat anomaly within the superconducting state. We interpret this anomaly as a signature of a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) inhomogeneous superconducting state. We obtain similar results for H || [001], with FFLO state occupying a smaller part of the phase diagram.
@article{arxiv.cond-mat/0304420,
title = {Fulde-Ferrell-Larkin-Ovchinnikov Superconducting State in CeCoIn5},
author = {A. Bianchi and R. Movshovich and C. Capan and A. Lacerda and P. G. Pagliuso and J. L. Sarrao},
journal= {arXiv preprint arXiv:cond-mat/0304420},
year = {2009}
}
Comments
4 pages, 3 figures, submitted to Phys. Rev. Letters