Magnetic Resonance in a Concentrated Spin-Glass: Experiment and a Phenomenological Model

Abstract

The microwave spectrum of amorphous sputtered films of ${\mathrm{Gd}}_{0.37}$ ${\mathrm{Al}}_{0.63}$ exhibits a resonance which moves rapidly to lower fields as temperature is decreased below the paramagnetic Curie temperature at 30 K and which exhibits no anomaly at the spin-glass ordering temperature of 16 K. The shift of the resonance field is interpreted as an effective anisotropy field arising from local demagnetizing fields of the inhomogeneous magnetic system. The theory is also compared to earlier resonance results on CuMn.