Berlin 2015 – scientific programme

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SYSD: Symposium SKM Dissertation-Prize 2015

SYSD 1: Symposium SKM Dissertation-Prize 2015

SYSD 1.2: Invited Talk

Monday, March 16, 2015, 11:25–11:50, HE 101

Dynamics of a Quantum Spin Liquid — •Johannes Knolle — T.C.M. Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom — Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany

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-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 model. 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}₂IrO₃ or α-RuCl₃ compounds, realize some of the physics of the Kitaev model. We discuss the current experimental situation, recent measurements and explore more generally the effect of breaking the integrability on response functions of Kitaev spin liquids.