Non-critical behaviour of the antiferromagnetic frustrated spinel ZnCr_1.6Ga_0.4O₄near its freezing temperature

Abstract

Many experimental results have indicated the existence of a freezing temperature of about 2.5 K and an overall behaviour equivalent to that of a spin glass state. The analysis of field cooled DC magnetisation measurements however shows that no critical behaviour appears in the first coefficients of the non-linear susceptibility. It is suggested that the very high degree of frustration prevents the development of a true spin glass transition. A simple model with uncompensated antiferromagnetic clusters consistently accounts for the observed properties.