Peering into the darkness: visongenerated photon mass in quantum spin ice
Abstract
Describing experimental signatures of quantum spin ice has been the focus of many theoretical efforts, as definitive experimental verification of this candidate quantum spin liquid is yet to be achieved. Gapped excitations known as visons have largely eluded those efforts. We provide a theoretical framework, which captures their dynamics and predicts new signatures in the magnetic response. We achieve this by studying the ringexchange Hamiltonian of quantum spin ice in the large$s$ approximation, taking into account the compact nature of the emergent $U(1)$ gauge theory. We find the stationary solutions of the action  the instantons  which correspond to visons tunneling between lattice sites. By integrating out the instantons, we calculate the effective vison Hamiltonian, including their mass. We show that in the ground state virtual vison pairs simply renormalise the speed of light. At low temperatures, however, thermally activated visons form a Debye plasma and introduce a mass gap in the photon spectrum, equal to the plasma frequency, which we calculate as a function of temperature. We demonstrate that this dynamical mass gap should be visible in energyresolved neutron scattering spectra but not in the energyintegrated ones. We also show that it does not lead to confinement of static spinons.
 Publication:

arXiv eprints
 Pub Date:
 October 2019
 arXiv:
 arXiv:1911.00097
 Bibcode:
 2019arXiv191100097K
 Keywords:

 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 Phys. Rev. B 102, 125113 (2020)