${\mathrm{CeCoIn}}_5$ is an anomalous superconductor which exhibits a high-magnetic-field phase that consists of a modulated magnetic coupling together with persistent superconducting order. Here we use a generic microscopic model to argue that this state is a pattern of coexisting condensates: a $d$-wave singlet superconducting (SC) state, a staggered $\pi$-triplet SC state, and a spin density wave (SDW). Our microscopic picture allows a calculation of the phase diagram, and physical consequences including NMR. We interpret the appearance of the SDW order in the $Q$ phase as being induced by odd-triplet pairing.

• Received 27 January 2010

DOI:https://doi.org/10.1103/PhysRevLett.104.216403