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 Yb2Ti2O7.
@article{arxiv.1910.09556,
title = {Analytical theory of pyrochlore cooperative paramagnets},
author = {Akshat Pandey and Roderich Moessner and Claudio Castelnovo},
journal= {arXiv preprint arXiv:1910.09556},
year = {2020}
}