Mixed valence on a pyrochlore lattice — LiV2O4 as a geometrically frustrated magnet

Above 40K, the magnetic susceptibility of the heavy Fermion spinel LiV2O4 has many features in common with those of geometrically frustrated magnetic insulators, while its room temperature resistivity comfortably exceeds the Mott–Regel limit. This suggests that local magnetic moments, and the underlying geometry of the pyrochlore lattice, play an important role in determining its magnetic properties. We extend a recently introduced tetragonal mean field theory for insulating pyrochlore antiferromagnets to the case where individual tetrahedra contain spins of different lengths, and use this as a starting point to discuss three different scenarios for magnetic and electronic transitions in LiV2O4. PACS. 71.27.+a Strongly correlated electron systems; heavy fermions – 71.10.-w Theory and models of many–electron systems – 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.