Resistivity of noble-metal-transition-metal spin glasses

Abstract

Following the existence of a 'hole' in the local field distribution P(H), the authors have divided the spin system of a spin glass into two groups: those lying at the lower bounds of P(H) are 'effective free' spins and the rest are interacting spins. New expressions for 'effective free' spin populations and interacting spin populations are incorporated into a modified Kondo theory and a spin-diffusion theory respectively. They have thereby obtained a model for magnetic resistivity. The authors analysed experimental data on AgMn, AuMn and CuMn spin glasses, using this model for best fitting of the data. The model gives a satisfactory description of the experimental behaviour for all these alloys. A new resistivity maximum is observed in the interacting spin resistivity at a temperature TSG, close to Tf, the temperature for the AC susceptibility cusp. The temperature Tm, of the resistivity maximum depends on impurity spin S, and it is related to the lower bounds Hc, of P(H).