The Search for Realizations of Quantum Spin Ice Ground States in Dipole-Octupole Pyrochlores
Bruce Gaulin
McMaster University
Wednesday, September 23, 2026
2:30 p.m.
In-person: QNC 1201
Abstract: The classical spin ice problem is a particular form of magnetic frustration that can give rise to a disordered ground state. It is equivalent to the problem of proton disorder in solid ice — hence the name. This problem was introduced in experiments on dipole pyrochlore magnets almost 30 years ago. Less than 10 years later, the quantum version of the same frustrated magnetism problem was theoretically developed, and it was realized that Quantum Spin Ice possesses an emergent quantum electrodynamics, with gapped monopole and gapless emergent photons as its elementary excitations.
Since these theoretical beginnings, we and others have been searching for experimental realizations of materials whose exotic low temperature properties can be described in terms of Quantum Spin Ice physics. That search has recently landed on a series of Ce-based pyrochlore insulators, Ce2Zr2O7, Ce2Hf2O7 and Ce2Sn2O7. However, there is a twist — the Ce3+ pseudo-spin 1/2 degree of freedom in these pyrochlore insulators possess both dipole and octupole character. So the anticipated ground state phase diagram can, in principle, display Quantum Spin Ices with both dipole and octupole flavour. I will mostly describe our recent efforts to experimentally understand these materials and how they relate to these proposed quantum disordered ground states.
View the full Fall Quantum Matters seminar schedule: Anton Burkov's website - Quantum Matter Seminars