Crystal field states of Tb3+ in the pyrochlore spin liquid Tb2Ti2O7 from neutron spectroscopy

TL;DR

This study uses neutron spectroscopy to precisely determine the crystal field states of Tb3+ in Tb2Ti2O7, confirming a non-Kramers doublet ground state and refining the crystal field model independently of other pyrochlores.

Contribution

It provides a new, independently refined crystal field model for Tb2Ti2O7 based on extensive neutron spectroscopy data, without relying on other materials.

Findings

Confirmed the non-Kramers doublet ground state with |+/-4> components.

Extended the crystal field spectrum measurements up to 120 meV.

Refined the crystal field potential model independently of other pyrochlore data.

Abstract

We report time-of-flight neutron scattering measurements of the magnetic spectrum of Tb3+ in Tb2Ti2O7. The data, which extend up to 120 meV and have calibrated intensity, enable us to consolidate and extend previous studies of the single-ion crystal field spectrum. We successfully refine a model for the crystal field potential in Tb2Ti2O7 without relying on data from other rare earth titanate pyrochlores, and we confirm that the ground state is a non-Kramers doublet with predominantly |+/-4> components. We compare the model critically with earlier models.