Electron Spin Resonance in Metallic Spin-Glasses aboveTg

Recent ESR measurements on the spin-glass $\mathrm{Ag}\mathrm{Mn}$ in the paramagnetic phase reveal an increase in the linewidth over the expected linear temperature dependence for $\frac{T}{T_g}\lesssim 3$. The Mori-Kawasaki formalism was used to calculate quantitatively the linewidth due to the broadening by the Dzyaloshinsky-Moriya anisotropy interaction of an exchange-narrowed line. With no adjustable parameters the authors explain the increase in linewidth, and they also relate the shift in the resonance to the imaginary part of the frequency-dependent self-energy.