Coexistence of d-wave superconductivity and antiferromagnetism induced by paramagnetic depairing

Abstract

It is shown theoretically that, in the superconducting state with dx 2-y2-pairing, a strong Pauli paramagnetic depairing (PD) induces not only the modulated Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state but also an incommensurate antiferromagnetic (AFM) (or spin-density wave) ordering with Q-vector nearly parallel to a gap node. In this mechanism of field-induced coexistence of the d-wave superconducting and AFM orders, a pair-density wave does not have to be assumed. It is argued that this is the common origin of both the coexistent FFLO and AFM phases of CeCoIn 5 and the AFM quantum critical behavior around the superconducting Hc2(0) seen in several unconventional superconductors. © Published under licence by IOP Publishing Ltd.