Long-range triplet proximity effect in multiply connected ferromagnet-superconductor hybrids

Phys. Rev. B 100, 014509

Abstract: Applying the linearized Usadel equations, we consider the nucleation of superconductivity in multiply connected mesoscopic superconductor/ferromagnet (S/F) hybrids such as a thin superconducting ring on a ferromagnet with a uniform in-plane magnetization $M$ and a spin-active S/F interface. We demonstrate that the exchange field in F provokes a switching between superconducting states with different vorticities which may increase the critical temperature($T_c$) of the superconductor in a magnetic field. We study the interplay between oscillations in $T_c$ due to the Little-Parks effect and oscillations in $T_c$ induced by the exchange field. Furthermore, we analyze the influence of long-range spin-triplet correlations on the switching between different vorticities.