Little-Parks effect in a superconducting loop with a magnetic dot

Abstract

We have studied the nucleation of superconductivity in a mesoscopic Al loop, enclosing a magnetic dot with the perpendicular magnetization. The superconducting phase boundary $T_c\mathrm{}\left(B\right),$ determined from transport measurements, is asymmetric with respect to the polarity of an applied magnetic field. The maximum critical temperature has been found for a finite applied magnetic field, which is antiparallel to the magnetization of the dot. Theoretical phase boundary shows a good agreement with the experimental data.