Theoretical Physics

14 July 2016
Time: 15:00 to 16:00
Location: EC Stoner 8.90

Theoretical Physics Seminar: Johannes Knolle (Cambridge)

Dynamics of a quantum spin liquid

Topological states of matter present a wide variety of striking new phenomena, most prominently is the fractionalization of electrons. Their detection, however, is fundamentally complicated by the lack of any local order. While there are now several instances of candidate topological spin liquids, their identification remains challenging. Here, we address one of the key questions: How can a quantum spin liquid phase be diagnosed in experiments? We find that the dynamical response can serve as a valuable tool for diagnosing quantum spin liquids. We provide a complete and rarely available exact theoretical study of the dynamical structure factor and the inelastic Raman scattering response of a two- and three- dimensional quantum spin liquid in Abelian and non-Abelian phases. We show that there are salient signatures of the Majorana fermions and gauge fluxes emerging in Kitaev’s honeycomb models. Our analysis identifies new varieties of the venerable X-ray edge problem and explores connections to the physics of quantum quenches. A number of proposals suggest that some materials with strong spin-orbit coupling, e.g. {Na/Li}2IrOor α-RuClcompounds, realize some of the physics of the Kitaev model. We discuss the current experimental situation and recent measurements.



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