The upper critical magnetic field H of the superconducting state of CeCoIn is anisotropic, in accordance with the crystal structure and other physical properties. For magnetic fields applied along the [100] direction, H amounts to approximately 11.6 T, and H for fields along the [001] directions to 4.95 T.
The superconducting order parameter has d-wave symmetry, as established by several experiments, such as scanning tunneling microscopy (STM) and spectroscopy (STS).
Detailed studies close to the critical field have been performed on CeCoIn, and indications were found that certain regimes in the phase diagram of this material should be interpreted in terms of the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) phase.
Subsequently, the neutron-diffraction experiments showed that this regime features a more complex phase that also exhibits incommensurate antiferromagnetic order, a so-called Q phase.
Evidence for a delocalization quantum phase transition without symmetry breaking is presented.