Quantum Excitations in Quantum Spin Ice

TL;DR

This paper investigates quantum spin ice, especially Yb2Ti2O7, revealing strong quantum fluctuations and proposing it as a candidate for a quantum spin liquid with a well-characterized Hamiltonian.

Contribution

It provides a unifying framework for quantum spin ice, extracts Hamiltonian parameters for Yb2Ti2O7, and suggests its potential as a quantum spin liquid with a quantum critical point.

Findings

Yb2Ti2O7 exhibits strong quantum fluctuations.

The Hamiltonian supports a Coulombic quantum spin liquid ground state.

Yb2Ti2O7 is the first quantum spin liquid candidate with a quantitatively known Hamiltonian.

Abstract

Recent work has highlighted remarkable effects of classical thermal fluctuations in the dipolar spin ice compounds, such as "artificial magnetostatics", manifesting as Coulombic power-law spin correlations and particles behaving as diffusive "magnetic monopoles". In this paper, we address quantum spin ice, giving a unifying framework for the study of magnetism of a large class of magnetic compounds with the pyrochlore structure, and in particular discuss Yb2Ti2O7 and extract its full set of Hamiltonian parameters from high field inelastic neutron scattering experiments. We show that fluctuations in Yb2Ti2O7 are strong, and that the Hamiltonian may support a Coulombic "Quantum Spin Liquid" ground state in low field and host an unusual quantum critical point at larger fields. This appears consistent with puzzling features in prior experiments on Yb2Ti2O7. Thus Yb2Ti2O7 is the first quantum spin liquid candidate in which the Hamiltonian is quantitatively known.