Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Departmental Colloquium - Quantum Spin Ice Physics and Emergent QED in Pyrochlore Magnets

Bruce Gaulin
McMaster University

Date: Friday, January 23, 2015
Time: 1:30 p.m
Location: Stirling Theatre A

Abstract:

Different combinations of magnetic interactions and anisotropies relevant to magnetism on the pyrochlore lattice, a cubic network of corner-sharing tetrahedra,  are known to lead to different exotic, and often disordered, ground states. One such state that has been of much topical interest is "spin ice". The elementary excitations within the spin ice ground state are describable as diffusing magnetic monopoles, and much theory and experiment have focussed on the extent to which this description is appropriate to real pyrochlore magnets.  As I'll discuss, this spin ice description is entirely classical, and we and others have been interested in identifying a quantum variant of this problem. I'll describe our progress in understanding a particular pyrochlore magnet, Yb2Ti2O7, in the context of quantum spin ice, mostly using time-of-flight neutron scattering. Along the way, I'll briefly discuss recent theory that suggests an emergent quantum electrodynamics is present within quantum spin ice, with elementary excitations that include both electric and magnetic monopoles, as well as gauge photons.