Disorder-Induced Entanglement in Spin Ice Pyrochlores

TL;DR

This paper demonstrates that disorder in non-Kramers spin ice materials induces quantum entanglement, transforming classical spin ice into a quantum spin liquid with emergent gauge structures and fractional excitations, revealing a disorder-driven quantum phase transition.

Contribution

It introduces the concept that disorder can induce quantum entanglement in spin ice, leading to a transition from classical to quantum spin liquids with emergent gauge fields.

Findings

Disorder transforms classical spin ice into a quantum spin liquid.

Identification of a transition from Coulombic spin liquid to Mott glass and then to a glassy phase.

Disorder level controls the quantum phases and emergent excitations.

Abstract

We propose that in a certain class of magnetic materials, known as non-Kramers 'spin ice,' disorder induces quantum entanglement. Instead of driving glassy behavior, disorder provokes quantum superpositions of spins throughout the system, and engenders an associated emergent gauge structure and set of fractional excitations. More precisely, disorder transforms a classical phase governed by a large entropy, classical spin ice, into a quantum spin liquid governed by entanglement. As the degree of disorder is increased, the system transitions between (i) a "regular" Coulombic spin liquid, (ii) a phase known as "Mott glass," which contains rare gapless regions in real space, but whose behavior on long length scales is only modified quantitatively, and (iii) a true glassy phase for random distributions with large width or large mean amplitude.