Relaxation processes and kinetic phenomena in narrow-gap superconductors
Abstract
The possibility of using the two-band superconductor model1 by taking into consideration the electron scattering at the lattice defects and the correlation interaction of the wide- and narrow-band electrons for describing the kinetic properties of high-Tc superconductors (HTS) in normal state is discussed. Specific features of the relaxation processes in the electron system of a narrow-band conductor, viz. the non-Born impurity scattering in the region of band overlapping, and an anomalous increase in the electron–electron scattering for a partially filled narrow band, are explained. The temperature dependence of resistance, caused by the interference of various relaxation mechanisms, contains a broad-linear region typical of HTS, while the thermoelectric coefficient has an anomalously large value which reverses its sign upon a variation of temperature and electron concentration. A comparison is made between the kinetic and thermodynamic properties of the two-band model for different values of its microscopic parameters.