Condensed Matter Seminar

Leon Balents
Kavli Institute for Theoretical Physics, UCSB

Tuesday, April 14, 2009; 4:00 pm in JFB 334

Spin-orbit effects in frustrated quantum magnets with orbital degeneracy

Spin-orbit coupling can be an important ingredient in transition metal compounds in which orbital degeneracy is present. I will describe theoretical studies of two materials, FeSc₂S₄ and Na₄Ir₃O₈, in which we believe "strong" spin orbit effects are present. In FeSc₂S₄, the competition of spin orbit and exchange leads to a quantum critical point, and an explanation for the observed spin-orbital-liquid behavior. In Na₄Ir₃O₈, we argue that strong spin orbit quenches the orbital degeneracy and leads to effective J=1/2 moments, as observed experimentally. The status of the resulting quantum spin liquid on an hyperkagome lattice will be discussed in this context.