Theory of electron-spin-resonance linewidth and line-shift effects in spin-glasses with anisotropy and zero remanent magnetization

The dramatic increase in the width of the electron-spin-resonance line in Ruderman-Kittel-Kasuya-Yosida spin-glasses at temperatures above the transition temperature $T_f$, recently regarded as evidence in favor of a phase transition, is explained as an effect of the small measuring frequency. The present theory also gives an explanation for the line-shift behavior as a function of the measuring frequency and the temperature.