Field induced spin ice like orders in spin liquid Tb$_2$Ti$_2$O$_7$

TL;DR

This study reveals how magnetic fields induce spin ice-like and antiferromagnetic structures in the spin liquid Tb$_2$Ti$_2$O$_7$, using neutron diffraction to analyze the complex field and temperature-dependent magnetic order.

Contribution

It provides a detailed experimental analysis of field-induced magnetic structures in Tb$_2$Ti$_2$O$_7$, combining unpolarized and polarized neutron data with a local susceptibility model, revealing new magnetic phases.

Findings

Field induces spin ice-like order at low fields and temperatures.

A second antiferromagnetic-like phase appears above 2 T and below 2 K.

Field-induced distortions suggest magnetostriction effects.

Abstract

We have studied the field induced magnetic structures in the spin liquid Tb$_2$Ti$_2$O$_7$, in a wide temperature (0.3$<$$T$$<$270 K) and field (0$<$$H$$<$7 T) range, by single crystal neutron diffraction with $\bf{H}$ // [110] axis. We combined unpolarized neutron data with polarized ones, analyzed within the local susceptibility model. A ferromagnetic-like structure with $\bf{k}$ = 0 propagation vector is induced, whose local order at low field and low temperature is akin to spin ice. The four Tb ions separate in $\alpha$ and $\beta$ chains having different values of the magnetic moments, which is quantitatively explained by taking the crystal field anisotropy into account. Above 2 T and below 2 K, an antiferromagnetic-like structure with $\bf{k}$ = (0,0,1) is induced besides the $\bf{k}$ = 0 structure. It shows a reentrant behavior and extends over a finite length scale. It occurs together with a broadening of the nuclear peaks, which suggests a field induced distortion and magnetostriction effect.