It is shown that the ESR modes observed in Cu: Mn alloys can be explained in terms of an Edwards-Anderson-type theory for a spin-glass when an anisotropy energy is included. Unlike other theories, the present one involves the conventional form for this anisotropy, UK=Ksin2θ, where θ is the angle the local microscopic magnetization makes with the symmetry rather than equilibrium direction. The present theory is distinguished by a predicted, but as yet unobserved, angular dependence of single-crystal samples with axial symmetry.
Barnes, S. E., "Electron-Spin-Resonance Modes and the Edwards-Anderson Theory of the Spin-Glass State" (1981). Physics Articles and Papers. 49.