Dynamically-Induced Frustration as a Route to a Quantum Spin Ice State in Tb2Ti2O7 via Virtual Crystal Field Excitations and Quantum Many-Body Effects

TL;DR

This paper proposes that Tb2Ti2O7 is a quantum spin ice resulting from quantum fluctuations near a phase boundary, explained through a model considering virtual crystal field excitations and many-body effects.

Contribution

It introduces a quantum model of independent tetrahedra that accounts for the low temperature properties of Tb2Ti2O7, highlighting the role of virtual crystal field excitations in inducing quantum spin ice behavior.

Findings

Tb2Ti2O7 is a quantum spin ice due to quantum fluctuations.

Proximity to a Nél to spin ice phase boundary enhances quantum effects.

Neutron scattering can experimentally test the quantum spin ice state.

Abstract

The Tb$_2$Ti$_2$O$_7$ pyrochlore magnetic material is attracting much attention for its {\em spin liquid} state, failing to develop long range order down to 50 mK despite a Curie-Weiss temperature $\theta_{\rm CW} \sim -14$ K. In this paper we reinvestigate the theoretical description of this material by considering a quantum model of independent tetrahedra to describe its low temperature properties. The naturally-tuned proximity of this system near a N\'eel to spin ice phase boundary allows for a resurgence of quantum fluctuation effects that lead to an important renormalization of its effective low energy spin Hamiltonian. As a result, Tb$_2$Ti$_2$O$_7$ is argued to be a {\em quantum spin ice}. We put forward an experimental test of this proposal using neutron scattering on a single crystal.