Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 16: Focus Session: Dynamics, Topology, and Fractionalisation
TT 16.3: Hauptvortrag
Montag, 31. März 2014, 16:00–16:30, HSZ 01
Dynamics of Majorana Fermions in a Quantum Spin Liquid — •John Chalker1, Johannes Knolle2, Dmitry Kovrizhin3, and Roderich Moessner2 — 1Physics Department, Oxford University, Oxford, U.K. — 2Max Planck Institute for Physics of Complex Systems, Dresden — 3Cavendish Laboratory, Cambridge University, U.K.
The study of spin liquids has been central to advancing our understanding of correlated phases of quantum matter ever since Anderson’s 1973 proposal of the resonating valence bond liquid state. However, detailed theoretical investigations of dynamics in spin liquids are hampered by the lack of suitable approaches, with analytical descriptions restricted to general features and numerical methods limited to small systems sizes, to models with a robust excitation gap, or ones that avoid the sign problem in quantum Monte Carlo.
In this setting the Kitaev honeycomb model provides a benchmark: it gives
an exactly solvable model in which spins dissolve into new degrees of freedom – fluxes of a Z2 gauge field and Majorana fermions moving in this field – and is representative of a broad class of systems. I will present results from a numerically exact calculation of the dynamical structure factor for this system. These include counter-intuitive manifestations of quantum number fractionalisation, such as a neutron scattering response with a gap even in the
presence of gapless excitations, and a sharp component despite the fractionalisation of electron spin.
J. Knolle, D. L. Kovrizhin, J. T. Chalker, and R. Moessner, arXiv:1308.4336