Structural distortion and the spin liquid state in Tb2Ti2O7

TL;DR

This paper demonstrates that a specific structural distortion in Tb2Ti2O7 explains the observed spin liquid behavior, highlighting the importance of collective tetrahedral spin states over individual spins.

Contribution

It introduces a model where a k=0, A_{2u} distortion leads to isolated tetrahedra, emphasizing collective spin states as key to the spin liquid state in Tb2Ti2O7.

Findings

Structural distortion isolates tetrahedra in Tb2Ti2O7

Collective spin states explain spin liquid features

Effective tetrahedral interactions are weak and anisotropic

Abstract

It is shown that a k=0, A_{2u} distortion of the terbium tetrahedral network in Tb2Ti2O7 accounts for the apparent isolation of single tetrahedra as seen in neutron scattering studies. Single tetrahedron collective spin states, rather than individual spins, account for the main features of the spin liquid state, namely, fluctuating local moments and the absence of long range order. Singlet and doublet collective spin ground states are considered. An effective interaction between tetrahedra on the fcc lattice is derived and found to be weak and anisotropic.