The theoretical analysis of electronic thermal properties of the interfaces between multiband superconductors and a normal metal

摘要

Investigations of the electronic thermal properties of the interfaces between a normal metal and high-temperature superconductors are important for correct design of modern low-temperature electronic refrigerators and bolometers. Multiband superconductivity, recently discovered in ferropnictides and in magnesium diboride, is the suitable choice due to isotropic order parameter in it, in contrast with strongly anisotropic d-wave superconductivity in high-T_c cuprates, which is destructive for electronic refrigeration and bolometric applications. Moreover, recent calculations of Andreev spectra and subgup bound states in ferropnictides, taking into account coherent multiband interference effects in s_± sign-reversal order parameter model, predict possible suppression of Andreev reflection for clean boundaries between ferropnictides and a normal metal. This Andreev reflection suppression can improve electronic refrigerator quality. Up to now there was no calculation of electronic thermal properties of the interfaces between a normal metal and novel multiband superconductors. In this paper we calculate the thermal flux and electronic thermal conductivity of the boundary between normal metal and novel multiband superconductors. In this calculations both s_(++) and s_± sign-reversal order parameter models for multiband superconductor is used, taking into account coherent multiband interference effect.