Quantum spin glass in anisotropic dipolar systems

TL;DR

This paper investigates the nature of the spin-glass phase in the Hx compound, emphasizing the importance of hyperfine interactions and off-diagonal dipolar terms at finite transverse fields, challenging the quantum criticality assumption.

Contribution

It provides a detailed analysis showing that the system is not a spin glass at finite transverse fields and highlights the significance of complex interactions beyond the quantum Ising model.

Findings

The system is well described by the classical Ising model at zero transverse field.

Finite transverse fields require considering hyperfine and off-diagonal dipolar interactions.

The system does not exhibit quantum criticality at finite transverse fields.

Abstract

The spin-glass phase in the $\LHx$ compound is considered. At zero transverse field this system is well described by the classical Ising model. At finite transverse field deviations from the transverse field quantum Ising model are significant, and one must take properly into account the hyperfine interactions, the off-diagonal terms in the dipolar interactions, and details of the full J=8 spin Hamiltonian to obtain the correct physical picture. In particular, the system is not a spin glass at finite transverse fields and does not show quantum criticality.