SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 47: Quantum-Critical Phenomena

TT 47.13: Vortrag

Donnerstag, 30. März 2023, 12:45–13:00, HSZ 204

Quantum criticality of Heisenberg systems with long-range interactions — •Patrick Adelhardt and Kai Phillip Schmidt — Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)

The majority of numerical approaches investigating long-range quantum systems is restricted to one-dimensional systems and systems in two dimensions with quickly decaying long-range interactions. While models with discrete symmetries like the long-range transverse-field Ising model have been studied thoroughly, much less is known about long-range models with continuous symmetries where long-range interactions can cricumvent the Hohenberg-Mermin-Wagner theorem in one dimension allowing the spontaneous breaking of continuous symmetries or can give rise to massive excitations violating Goldstone's theorem. We study the breakdown of the rung-singlet phase in the quasi one-dimensional Heisenberg ladders as well as two-dimensional Heisenberg bilayer systems with algebraically decaying long-range interactions. To this end we use the method of perturbative continuous unitary transformations (pCUT) as a white graph expansion with classical Monte Carlo simulations yielding high-order series in the thermodynamic limit about the limit of isolated dimers. This allows us to determine the critical point as well as critical exponents as a function of the decay exponent.