Field-driven transitions in the dipolar pyrochlore antiferromagnet Gd₂Ti₂O₇

Abstract

We present a mean-field theory for magnetic-field-driven transitions in dipolar coupled gadolinium titanate Gd₂Ti₂O₇ pyrochlore system. Low-temperature neutron scattering yields a phase that can be regarded as a eight sublattice antiferromagnet, in which long-ranged ordered moments and fluctuating moments coexist. Our theory gives parameter regions where such a phase is realized, and predicts several other phases, with transitions amongst them driven by magnetic field as well as temperature. We find several instances of local disorder parameters describing the transitions.