Enhancement of superconductivity mediated by antiferromagnetic squeezed magnons*

We theoretically investigate magnon-mediated superconductivity in a heterostructure consisting of a normal metal and a two-sublattice antiferromagnetic insulator. The attractive electron-electron pairing interaction is caused by an interfacial exchange coupling with magnons residing in the antiferromagnet, resulting in p-wave, spin-triplet superconductivity in the normal metal. Our main finding is that one may significantly enhance the superconducting critical temperature by coupling the normal metal to only one of the two antiferromagnetic sublattices employing, for example, an uncompensated interface. Employing realistic material parameters, the critical temperature increases from vanishingly small values to significantly larger values than 1 K as the interfacial coupling becomes strongly sublattice-asymmetric. We provide a general physical picture of this enhancement mechanism based on the notion of squeezed bosonic eigenmodes.