Fluctuation-Induced Interactions and the Spin Glass Transition in $Fe_2TiO_5$

TL;DR

This paper explores the anisotropic spin-glass transition in Fe2TiO5, revealing nanoscale antiferromagnetic regions and proposing a mean-field theory that links fluctuation-induced interactions to the transition.

Contribution

It introduces a novel mean-field replica theory for the anisotropic spin-glass transition driven by fluctuation-induced interactions in Fe2TiO5.

Findings

Nanoscale surfboard-shaped antiferromagnetic regions form below 55 K.

The transition involves freezing of transverse magnetization fluctuations.

A mean-field theory reveals a magnetic van der Waals effect.

Abstract

We investigate the spin-glass transition in the strongly frustrated well-known compound $Fe_2TiO_5$. A remarkable feature of this transition, widely discussed in the literature, is its anisotropic properties: the transition manifests itself in the magnetic susceptibly only along one axis, despite $Fe^{3+}$ $d^5$ spins having no orbital component. We demonstrate, using neutron scattering, that below the transition temperature $T_g = 55 K$, $Fe_2TiO_5$ develops nanoscale surfboard shaped antiferromagnetic regions in which the $Fe^{3+}$ spins are aligned perpendicular to the axis which exhibits freezing. We show that the glass transition may result from the freezing of transverse fluctuations of the magnetization of these regions and we develop a mean-field replica theory of such a transition, revealing a type of magnetic van der Waals effect.