${\rm LiHo_xY_{1-x}F_4}$ as a random field Ising ferromagnet

TL;DR

This paper demonstrates that diluted ${ m LiHo_xY_{1-x}F_4}$ under a transverse field acts as a classical random field Ising model, allowing independent control of effective fields and dilution, with implications for different dimensions.

Contribution

It establishes an exact equivalence between the diluted ${ m LiHo_xY_{1-x}F_4}$ system and the classical RF Ising model under certain conditions, enabling controlled experimental realization.

Findings

System behaves as a RF Ising model at low transverse fields.

Effective RF can be tuned independently of other parameters.

Implications for 1D, 2D, and 3D systems are discussed.

Abstract

As a result of the interplay between the intrinsic off-diagonal terms of the dipolar interaction and an applied {\it transverse} field $H_t$, the diluted ${\rm LiHo_xY_{1-x}F_4}$ system at x$> 0.5$ is equivalent to a ferromagnet in a longitudinal random field (RF). At low $H_t$ the quantum fluctuations between the Ising like doublet states are negligible, while the effective induced RF is appreciable. This results in a practically exact equivalence to the classical RF Ising model. By tuning $H_t$, the applied longitudinal field, and the dilution, the Ising model can be realized in the presence of an effective RF, transverse field, and constant longitudinal field, all independently controlled. The experimental consequences for $D=1,2,3$ dimensions are discussed.