The spin-1/2 triangular-lattice antiferromagnet is a central model in frustrated quantum magnetism: it is the first two-dimensional magnet proposed to host a SU(2) symmetric resonating valence-bond ground-state and its fractionalized magnetic excitations. Although it is now accepted that the model, at least in its simplest Heisenberg form, orders magnetically, it remains intimately associated with the concepts of quantum spin-liquid and exotic magnetic excitations. In the last few years, advances in materials discovery, crystal growth, neutron spectroscopy and theory have fueled a lively triangular-lattice antiferromagnet “renaissance”. In this talk, I will describe recent neutron scattering investigations on two realizations of this model: the transition metal compound Ba3CoSb2O9 and the rare-earth system YbMgGaO4. Experimental results elucidate the role of quantum fluctuations, spin-orbit coupling, chemical disorder, and non-linear effects in generating anomalous spin dynamics in these materials. This project is supported by the NSF under grant DMR-1750186.

Host: Ribhu Kaul