Quantum spin fluctuations in the dipolar Heisenberg-like rare earth pyrochlores

TL;DR

This paper investigates quantum spin fluctuations in dipolar Heisenberg-like rare earth pyrochlores, showing that classical ground states are stable against quantum effects, with long-range dipole interactions influencing symmetry and anisotropy.

Contribution

It provides a detailed numerical analysis of quantum fluctuations in dipolar pyrochlores, highlighting the stability of classical ground states and the effects of long-range dipole interactions.

Findings

Classical ground states are stable against quantum fluctuations.

Long-range dipole interactions restore symmetry and reduce anisotropy gap.

Minimal deviation from full magnetic order at zero temperature.

Abstract

The magnetic pyrochlore oxide materials of general chemical formula R2Ti2O7 and R2Sn2O7 (R = rare earth) display a host of interesting physical behaviours depending on the flavour of rare earth ion. These properties depend on the value of the total magnetic moment, the crystal field interactions at each rare earth site and the complex interplay between magnetic exchange and long-range dipole-dipole interactions. This work focuses on the low temperature physics of the dipolar isotropic frustrated antiferromagnetic pyrochlore materials. Candidate magnetic ground states are numerically determined at zero temperature and the role of quantum spin fluctuations around these states are studied using a Holstein-Primakoff spin wave expansion to order 1/S. The results indicate the strong stability of the proposed classical ground states against quantum fluctuations. The inclusion of long range dipole interactions causes a restoration of symmetry and a suppression of the observed anisotropy gap leading to an increase in quantum fluctuations in the ground state when compared to a model with truncated dipole interactions. The system retains most of its classical character and there is little deviation from the fully ordered moment at zero temperature.