Microwave conductivity due to impurity scattering in cuprate superconductors

Microwave surface impedance measurements on cuprate superconductors provide crucial information about the effect of impurity scattering on quasiparticle transport; however, acquiring a full understanding of the effect of impurity scattering on quasiparticle transport is still challenging. Here, starting from a homogenous electron propagator , the related microscopic octet scattering model, which are obtained within the square-lattice t -J model in the fermion-spin representation, the effect of impurity scattering on low-temperature microwave conductivity in cuprate superconductors is investigated in the self-consistent T-matrix approach. The impurity -dressed electron propagator obtained in the Fermi-arc-tip approximation of the quasiparticle excitations and scattering processes is employed to derive the electron current-current correlation function by taking into account the impurity-induced vertex correction. It is shown that the microwave conductivity spectrum is non-Drude-like, with a sharp cusplike peak extending to zero energy and a high-energy tail falling slowly with energy. Moreover, the microwave conductivity decreases with an increase in the impurity concentration or with an increase in the strength of the impurity scattering potential. In striking contrast to the domelike shape of the doping dependence of the superconducting transition temperature, the microwave conductivity exhibits a reverse domelike shape of the doping dependence. The theory also shows that the unconventional features of the microwave conductivity are generated by both the strong electron correlation and impurity scattering effects.