Hydrogenic states of monopoles in diluted quantum spin ice

TL;DR

This paper explores how quantum effects influence monopole excitations in diluted quantum spin ice, revealing hydrogenic bound states and providing a method to detect these phenomena experimentally.

Contribution

It introduces the concept of hydrogenic monopole-vacancy bound states in diluted quantum spin ice and offers an analytical approach to study their experimental signatures.

Findings

Quantum effects are prominent in gauge-charged monopoles.

Hydrogenic bound states form between monopoles and vacancies.

An analytical expression for neutron scattering structure factor is derived.

Abstract

We consider the effect of adding quantum dynamics to a classical topological spin liquid, with particular view to how best to detect its presence in experiment. For the Coulomb phase of spin ice, we find quantum effects to be most visible in the gauge-charged monopole excitations. In the presence of weak dilution with nonmagnetic ions we find a particularly crisp phenomenon, namely the emergence of hydrogenic excited states in which a magnetic monopole is bound to a vacancy at various distances. Via a mapping to an analytically tractable single particle problem on the Bethe lattice, we obtain an approximate expression for the dynamic neutron scattering structure factor.