Interpretation of the temperature dependence of the electron-paramagnetic-resonance linewidth in Ag-Mn spin-glasses

We present a theory for the temperature dependence of the electron-paramagnetic-resonance linewidth in Ag-Mn spin-glasses in the region above $T_g$. Our approach differs from the microscopic theory of Levy et al. in that we use two-spin correlation functions which are compatible with the results of neutron spin-echo studies on Cu-Mn spin-glasses. The analysis, which is also applicable to paramagnetic resonance in other spin-glasses which have similar spin dynamics, pertains to the region 1.1$T_g$≲T≲3$T_g$. We obtain scaling behavior for the critical part of the linewidth and the dynamic line shift with effective exponents for the characteristic time and zero-frequency linewidth which are in agreement with the results obtained for Ag–2.6 at. % Mn. We also make a connection between the linewidth and the effective correlation time measured in muon-spin-rotation studies. We find that the effective exponent for the correlation time in Ag–1.6 at. % Mn is consistent with the exponents for the resonance linewidth.