Tb$_2$Ti$_2$O$_7$, a two singlet spin-liquid pyrochlore

TL;DR

This paper explains why the pyrochlore compound Tb$_2$Ti$_2$O$_7$ remains in a spin-liquid state at very low temperatures, contrary to theoretical predictions of magnetic ordering.

Contribution

It introduces a model based on Jahn-Teller-like distortion and two-singlet coupling to account for the persistent spin-liquid behavior.

Findings

No magnetic order observed down to 0.05 K

Jahn-Teller-like distortion explains spin-liquid state

Two-singlet system coupled by exchange accounts for experimental results

Abstract

The pyrochlore compound \tbti\ is known to remain in a spin-liquid state down to the lowest attainable temperature (0.05\,K), whereas current theories predict it should order into an antiferromagnetic structure. A number of models have been developed in order to resolve this discrepancy, but they could not obtain a spin-liquid ground state. We present here an explanation for the lack of magnetic order in \tbti\ based on the presence of a Jahn-Teller-like distortion from the local trigonal symmetry and on the physics of the two-singlet system coupled by exchange.