Fragmentation in Frustrated Magnets -- A review

TL;DR

This review discusses the concept of fragmentation in spin liquids, where spins split into ordered and disordered components, highlighting theoretical and experimental insights, especially in relation to magnetic monopoles and phase diagrams.

Contribution

It provides a comprehensive overview of the theoretical framework and experimental evidence for fragmentation in frustrated magnets, expanding the understanding of spin liquid phases.

Findings

Fragmentation describes spin degrees of freedom splitting into ordered and disordered parts.

Relation between fragmentation and magnetic monopoles in spin ice is established.

Experimental observations support the existence of fragmented spin states in various systems.

Abstract

Spin liquids are exotic phases of matter that often support emergent gauge fields and quasi-particle excitations. While spin liquids are commonly known for remaining disordered, their definition has been extended to include phases with broken symmetry corresponding to (partial) long-range order, such as chiral and nematic spin liquids for example. For Coulomb spin liquids, this ordering can be quantitatively understood via a Helmholtz decomposition between divergence-free and divergence-full terms. This phenomenon has been coined fragmentation, where spin degrees of freedom fragment into two components; the fluctuating disordered part and the ordered one. In this review, we will cover the theoretical and experimental aspects of this growing field, in particular its relation to magnetic monopoles in spin ice, its phase diagram and the possibility to observe it in solid-state crystal and artificial networks.