Speaker: Alberto Hinojosa Alvarado, Physics Department
Abstract: We study the structure and symmetry of the superconducting gap in the presence of spin density wave (SDW) order in iron-based superconductors. We specifically consider co-existing SDW and superconducting orders in a model with circular hole pockets and elliptic electronic pockets. We show that SDW order generally induces a spin-triplet component of the gap, in addition to the conventional spin singlet. We further show that, in some range of temperatures below Tc, the phases of superconducting order parameters on different reconstructed Fermi surfaces differ by an amount other than 0 or pi, i.e., superconductivity directly reflects the breaking of time-reversal symmetry by SDW order.