Reentrant induced superconductivity in hybrid structure with high barrier transparency
Within the framework of the self-consistent effective field approximation of the time dependent perturbation theory, an influence of the electron tunneling on spontaneously induced order parameters in a hybrid structure «normal metal-superconductor» is considered. For a normal-metal model that does not take into account electron-electron scattering as well as electronphonon coupling, it has been obtained a critical barrier transparency corresponding to the disappearance of superconductivity in the ground state. The presence of incoherent excitations leads to a complex relationship between the effects of ordering, thermal fluctuations, and tunneling. Near the critical barrier transparency, this can stabilize a superconducting state in the certain temperature regions. As a result, a reentrant superconductivity phenomenon is observed. The studied spectral properties of the hybrid structure reflect existence of both coherent and incoherent elementary excitations.