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arXiv · 1910.09556

Analytical theory of pyrochlore cooperative paramagnets

Akshat Pandey·Roderich Moessner·Claudio Castelnovo
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Abstract

The pyrochlore lattice is associated with several potential and actual spin liquid phases as a result of its strong geometric frustration. At finite temperature, these can exhibit an unusually broad cross-over regime to a conventional paramagnet. Here, we study this regime analytically by showing how a single-tetrahedron Hamiltonian can extrapolate beyond the first term of a high-temperature expansion and yield insights into the build-up of correlations. We discuss how this unusual behaviour is brought about by the structure of the eigenspaces of the coupling matrix. Further interesting behaviour can appear for parameter values located near phase transitions: we find coexistence of $(111)$ rods and $(220)$ peaks in the structure factor, as observed in neutron scattering experiments on Yb$_2$Ti$_2$O$_7$.

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Akshat Pandey, Roderich Moessner, Claudio Castelnovo. 2020-03-06. Analytical theory of pyrochlore cooperative paramagnets. https://doi.org/10.1103/physrevb.101.115107

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