Glassy behaviour in pyrochlores: a spin glass approach

Using a model for antiferromagnetism in disordered systems with many sublattices, it is suggested that the spin glass behaviour in pyrochlore systems is basically due to fluctuations in the spin interactions quenched on the time scale of measurements. A mean field calculation is carried out for antiferromagnetism in structures with many sublattices. By allowing quenched disorder (fluctuations) in the exchange interactions, our results clearly exhibit the interplay between the effects of lattice frustration and disorder on the system's properties. Even small fluctuations in the exchange parameters do induce sizeable glassy behaviour in structures with many sublattices. Spin glass behaviour in apparently non-disordered systems, such as certain pyrochlores, may thus be accounted for within the present context.