# SKM 2023 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# TT: Fachverband Tiefe Temperaturen

## TT 42: Poster: Correlated Electrons I

### TT 42.21: Poster

### Mittwoch, 29. März 2023, 15:00–18:00, P2/OG2

**Quantum criticality of the frustrated transverse-field Ising model on a triangular lattic using enhanced perturbative continous unitary transformations** — •Lukas Schamriß^{1}, Matthias R. Walther^{1}, Dag-Björn Hering^{2}, and Kai P. Schmidt^{1} — ^{1}Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen, Germany — ^{2}Condensed Matter Theory, Technische Universität Dortmund, Otto-Hahn-Straße 4, 44221 Dortmund, Germany

Ising models in a transverse field are paradigmatic models for quantum phase transitions of various universality classes which occur depending on the lattice geometry and the choice of antiferromagnetic of ferromagnetic coupling. We investigate the quantum phase diagram of the bilayer antiferromagnetic transverse field Ising model on a triangular lattice with an Ising-type interlayer coupling. Without a field, the model is known to host a classically disordered ground state, and in the limit of decoupled layers it exhibits the 3dXY transition of the corresponding single layer model. Our starting point for the unknown parts of the phase diagram is a high-order perturbative calculation from the limit of isolated dimers. Enhanced perturbative continuous unitary transformations (epCUTs) are used to derive series expansions for the ground state and the energy gap. These are refined by directly evaluated epCUTs (deepCUTs) which provide estimates which coincide with the perturbative series up to its respective order and add a non-perturbative correction. These allow to draw conclusions about the nature of occurring phase transitions.