Evidence for a ‘Higgs’ transition - not to be confused with a Higgs boson - in a magnetic material known as quantum spin ice is reported in Nature Communications this week. These findings indicate that quantum spin ice is a condensed matter system in which signatures of an emergent quantum electrodynamics are observable.

Spin ice is a state of matter in which monopole excitations can occur at low temperature. While the physics of spin ices has recently been the subject of significant interest in condensed matter physics, the behaviour of related materials in which quantum fluctuations play a prominent role has been less well understood. Using polarized neutron scattering, Shigeki Onoda and collaborators studied the rare-earth material ytterbium titanate and find it can be considered as a quantum version of spin ice. They report that it undergoes a ‘Higgs’ transition of emergent magnetic monopoles from a Coulomb liquid to a ferromagnetic phase.

The observation, the authors suggest, represents a step towards further understanding emergent quantum phases and elementary excitations in a condensed matter system.