Spin Density and Non-Collinear Magnetization in Frustrated Pyrochlore \tbti from Polarized Neutron Scattering

TL;DR

This study investigates the spin configurations and magnetic behavior of TbTi in a frustrated pyrochlore using polarized neutron scattering, revealing temperature-dependent reorientations and spin ice-like structures.

Contribution

It provides detailed insights into the temperature-dependent spin reorientation and local susceptibility changes in TbTi pyrochlore, highlighting the transition from Heisenberg to Ising behavior.

Findings

High-temperature collinear moments aligned with the field

Low-temperature spin ice-like structures with different moment magnitudes

Progressive change from Heisenberg to Ising behavior with decreasing temperature

Abstract

We used a local susceptibility approach in extensive polarized neutron diffraction studies of the spin liquid \tbti. For a magnetic field applied along the [110] and [111] directions, we found that, at high temperature, all Tb moments are collinear and parallel to the field. With decreasing temperature, the Tb moments reorient from the field direction to their local anisotropy axes. For the [110] field direction, the field induced magnetic structure at 10 K is spin ice-like, but with two types of Tb moments of very different magnitudes. For a field along [111], the magnetic structure resembles the so-called "one in-three out" found in spin ices, with the difference that all Tb moments have an additional component along the [111] direction due to the magnetic field. The temperature evolution of the local susceptibilities clearly demonstrates a progressive change from Heisenberg to Ising behavior of the Tb moments when lowering the temperature, which appears to be a crystal field effect.