EXPLANATION OF THE TEMPERATURE-DEPENDENCE OF RESISTIVITY IN HIGH-T(C) SUPERCONDUCTING BA0.6K0.4BIO3 BY ELECTRON-PHONON SCATTERING

The resistivity rho(T) of single crystals of the cubic high-T(c) superconductor Ba0.6K0.4BiO3 with T(c) = 30 K has been measured in the temperature range from 4.2 to 300 K. The experimental curve is well approximated in the framework of the classical electron-phonon model of resistivity by the Gruneisen type dependence using the phonon spectrum in the form of an acoustic branch and a widely separated narrow optical peak. Characteristic temperatures of the phonon spectrum - the Debye temperature I(D) of the acoustic branch and the Einstein temperature I(E) of the optical mode - and the ratio of contributions of acoustic and optical phonons to the resistivity were derived from the best fit of the theoretical curve rho(T) to the experimental one. The optical phonons of the oxygen breathing mode give a relatively larger contribution to the resistivity. Correspondingly, the contribution of optical phonons to the constant of electron-phonon interaction lambda is larger compared to the contribution of acoustic phonons.