STRUCTURES AND PHASE TRANSITIONS 28 PRESSURE INDUCED CRYSTALLIZATION OF A SPIN LIQUID

Tb2Ti2O7 is an insulating pyrochlore oxide in which localized Tb3+ spins occupy a lattice of corner-linked tetrahedra. Antiferromagnetic Heisenberg interactions on this lattice are highly frustrated, giving rise to macroscopic degeneracy in the ground state. In general this degeneracy is lifted by perturbations arising from chemical disorder or additional magnetic interactions, yielding either spin glass-like or long range ordering transitions. Tb2Ti2O7 is the only compound which remains in a fluctuating paramagnetic state down to 70 mK [1]. Short range antiferromagnetic correlations between the Tb spins develop below 100 K, corresponding to a “spin liquid ” state. The single ion ground state i