Bruce D. Gaulin, McMaster University

Thu, 10/11/2018 - 12:00pm
705 Pupin Hall


"Ground State Selection in Quantum Pyrochlore Magnets"

The pyrochlore lattice, a network of corner-sharing tetrahedra, is one of the most pervasive crystalline architectures in nature that supports geometrical frustration.  We and others have been interested in a family of rare earth pyrochlore magnets with local XY anisotropy, that can display quantum S=1/2 magnetism on such a lattice.  I will discuss up to three such magnets, Yb2Ti2O7, Er2Ti2O7 and Er2Pt2O7.  Yb2Ti2O7 has been discussed as a "quantum spin ice" candidate ground state system; Er2Ti2O7 displays a non-colinear Neel state at low temperature, selected by an order-by-disorder mechanism, while Er2Pt2O7 displays a novel "Palmer Chalker" state at low temperatures.  I will emphasize neutron scattering studies that we have carried out, and briefly discuss how their ground state selection can be understood in terms of anisotropic exchange on the pyrochlore lattice.

About the speaker

Bruce D. Gaulin is Distinguished University Professor and Brockhouse Chair in the Physics of Materials at McMaster University.  He received his BSc from McGill, before completing his PhD at McMaster in 1986.  Gaulin spent two years as a postdoc at Oak Ridge National Laboratory before returning to McMaster as an Assistant Professor, where he has been ever since.  His expertise lies in the application of neutron scattering techniques to topical problems in condensed matter physics, mainly focussing on quantum and frustrated magnetism.  Gaulin served as President of the Neutron Scattering Society of America from 2008 - 2012, and presently serves as President of the Canadian Association of Physicists.
More details can be found here.