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Ising pyrochlore magnets: Low temperature properties, ice rules and beyond

R. Siddharthan·B. S. Shastry·A. P. Ramirez·A. Hayashi·R. J. Cava·S. Rosenkranz
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Abstract

Pyrochlore magnets are candidates for spin-ice behavior. We present theoretical simulations of relevance for the pyrochlore family R2Ti2O7 (R= rare earth) supported by magnetothermal measurements on selected systems. By considering long ranged dipole-dipole as well as short-ranged superexchange interactions we get three distinct behaviours: (i) an ordered doubly degenerate state, (ii) a highly disordered state with a broad transition to paramagnetism, (iii) a partially ordered state with a sharp transition to paramagnetism. Thus these competing interactions can induce behaviour very different from conventional ``spin ice''. Closely corresponding behaviour is seen in the real compounds---in particular Ho2Ti2O7 corresponds to case (iii) which has not been discussed before, rather than (ii) as suggested earlier.

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R. Siddharthan, B. S. Shastry, A. P. Ramirez, A. Hayashi, R. J. Cava, S. Rosenkranz. 1999-03-22. Ising pyrochlore magnets: Low temperature properties, ice rules and beyond. https://doi.org/10.1103/physrevlett.83.1854

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