Thermodynamics of spin ice in staggered and direct (along the [111] axis) fields in the cluster approximation

Resumo

We have analyzed the low-temperature thermodynamic properties of spin ice in the staggered and direct (acting along the [111] axis) fields for rare-earth oxides with the chalcolamprite structure and general formula Re₂³⁺Me₂⁴⁺O₇^2-. Calculations have been performed in the cluster approximation. The results have been compared with experimental temperature dependences of heat capacity and entropy for Dy₂Ti₂O₇ compound for different values of the external field in the [111] direction. The experimental data and calculated results have also been compared for the Pr₂Ru₂O₇ compound with the antiferromagnetic ordering of magnetic moments of ruthenium ions, which gives rise to the staggered field acting on the system of rare-earth ions. The calculated temperature dependences of heat capacity and entropy are in good agreement with experimental data.