Abstract
The family of magnetic rare-earth pyrochlore oxides plays host to a diverse array of exotic phenomena, driven by the interplay between geometrical frustration and spin-orbit interaction, which leads to anisotropy in both magnetic moments and their interactions. In this article we establish a general, symmetry-based theory of pyrochlore magnets with anisotropic exchange interactions. Starting from a very general model of nearest-neighbor exchange between Kramers ions, we find four distinct classical ordered states, all with , competing with a variety of spin liquids and unconventional forms of magnetic order. The finite-temperature phase diagram of this model is determined by Monte Carlo simulation, supported by classical spin-wave calculations. We pay particular attention to the region of parameter space relevant to the widely studied materials , and . We find that many of the most interesting properties of these materials can be traced back to the “accidental” degeneracies where phases with different symmetries meet. These include the ordered ground-state selection by fluctuations in , the dimensional reduction observed in , and the lack of reported magnetic order in . We also discuss the application of this theory to other pyrochlore oxides.
20 More- Received 20 December 2013
- Revised 21 February 2017
DOI:https://doi.org/10.1103/PhysRevB.95.094422
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