Phase diagram with enhanced spin-glass region of mixed Ising / XY magnets LiHo$_{x}$Er$_{1-x}$F$_{4}$

TL;DR

This study maps the complex phase diagram of LiHo$_x$Er$_{1-x}$F$_4$, revealing multiple spin-glass phases and deviations from mean-field theory, advancing understanding of dipolar-coupled magnetic systems.

Contribution

It provides the first detailed experimental phase diagram of LiHo$_x$Er$_{1-x}$F$_4$, identifying new spin-glass phases and challenging existing theoretical predictions.

Findings

Embedded spin-glass phase within ferromagnetic structure below x=0.86

Ising spin-glass with needle-like clusters below x=0.57

Antiferromagnetically coupled spin-glass at x~0.3-0.1

Abstract

We present the experimental phase diagram of LiHo$_x$Er$_{1-x}$F$_4$, a dilution series of dipolar-coupled model magnets.The phase diagram was determined using a combination of AC susceptibility and neutron scattering. Three unique phases in addition to the Ising ferromagnet LiHoF$_4$ and the XY anti-ferromagnet LiErF$_4$ have been identified. Below $x=0.86$ an embedded spin-glass phase is observed, where a spin-glass exists within the ferromagnetic structure. Below $x=0.57$ an Ising spin-glass is observed consisting of frozen needle-like clusters. For $x \sim 0.3 - 0.1$ an antiferromagnetically coupled spin-glass occurs. A reduction of $T_C(x)$ for the ferromagnet is observed which disobeys the mean-field predictions that worked for LiHo$_x$Y$_{1-x}$F$_4$.