Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 42: Coherent Quantum Dynamics (joint session DY/TT)

DY 42.9: Vortrag

Donnerstag, 23. März 2017, 12:00–12:15, ZEU 160

Dynamics of the Kitaev-Heisenberg Model — •Ruben Verresen, Matthias Gohlke, Roderich Moessner, and Frank Pollmann — MPI for Physics of Complex Systems, Dresden, Germany

Quantum spin-liquids represent novel phases of matter that host emergent fractionalized excitations. The Kitaev-Heisenberg model is a two-dimensional model system in this context and relevant for recent experiments on putative quantum spin-liquid materials. We obtain the dynamical spin-structure factor for this model using a matrix-product state based method. This quantity can be compared to neutron scattering measurements and provides characteristic insights into the dynamics of the fractionalized excitations. We find significant broad high energy features beyond spin-wave theory even in the ordered phases when tuned near the spin-liquid regime. We then focus on the zig-zag phase of the Kitaev-Heisenberg model which is relevant for α-RuCl₃ and observe that the high energy part reveals features that were first seen in neutron scattering experiments, displaying proximate spin liquid physics. In particular we are led to the interpretation of the observed broad high energy features as the intersection of remnants of very diffuse spin-wave bands.