Physical properties of ferromagnetic-superconducting coexistent system from a mean-field model

Abstract

We study the nuclear relaxation rate $1∕{T}_{1}$ of a ferromagnetic-superconducting system from the mean field model proposed by Karchev et al. [Phys. Rev. Lett. 86, 846 (2001)]. This model predicts the existence of a set of gapless excitations in the energy spectrum which will affect the properties studied here, such as the density of states and, hence, $1∕{T}_{1}$. The study of the temperature variation of $1∕{T}_{1}$ (for $T<{T}_{c}$) shows that the usual Hebel-Slichter peak exists, but will be reduced because of the dominant role of the gapless fermions and the background magnetic behavior. We have also presented the temperature dependence of ultrasonic attenuation and the frequency dependence of electromagnetic absorption within this model. We are successful in explaining certain experimental results.