Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 94: Correlated Electrons: Other Theoretical Topics
TT 94.7: Talk
Thursday, March 15, 2018, 17:00–17:15, H 3010
Excitations of the square lattice Heisenberg model using tensor-network methods — •Ruben Verresen1,2, Frank Pollmann1, and Roderich Moessner2 — 1Technical University of Munich — 2Max-Planck-Institute for the Physics of Complex Systems
The square lattice Heisenberg model is a paradigmatic example of spontaneous symmetry breaking. Despite the apparent simplicity of the model, spin wave theory fails to describe its excitations at certain momenta. Opposing descriptions ---strongly-interacting magnons and emergent spinons--- have been proposed. We use a time-dependent density matrix renormalization group (DMRG) method to obtain the dynamical structure factor. In particular, we investigate its features by continuously tracking the spectral function as a function of a tuning parameter around a simple soluble limit. This leads us to a simple picture which already at low order in perturbation theory accounts for the features beyond SWT in a semi-quantitative way.