Phase transitions in superconductor/ferromagnet bilayer driven by spontaneous supercurrents
Zh. Devizorova, A. V. Putilov, I. Chaykin, С. В. Миронов, A. I. Buzdin
Abstract
We investigate the superconducting phase transition in a superconductor (S)/ferromagnet (F) bilayer with Rashba spin-orbit interaction at the S/F interface. This spin-orbit coupling produces spontaneous supercurrents flowing inside the atomic-thickness region near the interface, which are compensated by the screening Meissner currents [Mironov and Buzdin, Phys. Rev. Lett. 118, 077001 (2017)]. In the case of a thin superconducting film the emergence of the spontaneous surface currents causes an increase of the superconducting critical temperature, and we calculate the actual value of the critical temperature shift. We also show that in the case of a type-I superconducting film this phase transition can be of the first order. In the external magnetic field the critical temperature depends on the relative orientation of the external magnetic field and the exchange field in the ferromagnet. Also we predict the in-plane anisotropy of the critical current, which may open an alternative way for the experimental observation of the spontaneous supercurrents generated by the spin-orbit coupling.