Condensed Matter Seminar Series

Monte Carlo Studies of Spin Ice

Roger Melko

Unviersity of Waterloo

Wednesday February 22,  10:30 am,  Room 298,  Physics Building

Abstract: The name Spin Ice refers to a class of materials where rare-earth magnetic moments reside on a pyrochlore lattice of corner sharing tetrahedron.  Since their discovery in 1997 by Harris and colleagues, these materials (such as Dy2Ti2O7 and Ho2Ti2O7) have been a mainstay of classical frustrated magnetism research.  The analogy to ice arises because the magnetic groundstate is actually a degenerate manifold of equal-energy states, which leads to the same ground-state entropy as the proton-positional disorder in ice water, calculated by Linus Pauling.  The highly-constrained spin ice groundstate is an example of a classical "spin liquid", which harbors a fascinating array of phenomena, such as emergent monopole excitations and topological winding number sectors.  In this talk, I will give a basic introduction to the physics of spin ice from the perspective of Monte Carlo simulations, including the necessity of considering dipolar interactions, its behavior in magnetic fields, and topological order in ice systems with reduced dimensionality.