CPM Seminar

Local Probe Measurements of New Quantum Spin Liquid Candidates

Jeffrey Quilliam

Université de Sherbrooke

For many years, physicists have searched for the elusive quantum spin liquid (QSL) state - a disordered, long-range entangled ground state of a magnetic material induced by quantum fluctuations and frustration. Most often, this search has concentrated on highly frustrated lattices, such as the kagome lattice, and on spin-1/2 materials. However, here I will present two new avenues for the discovery of QSL states, both in the family known as the 6H-perovskites, Ba₃MSb₂O₉ with M=Cu and Ni. In the first case, orbital degrees of freedom appear to play a crucial role in an otherwise frustration-free honeycomb lattice. In the second material, spin-1 moments appear to be essential to generating a spin liquid ground state. Specifically, I will present local-probe measurements, �SR and NMR, on these materials, measurements that allow us to separate intrinsic magnetic properties from impurity effects and to probe the basic spin excitations out of these apparent spin liquid ground states.