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Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 23: Frustrated Magnets - General 1 (joint session TT/MA)

TT 23.12: Vortrag

Dienstag, 2. April 2019, 12:30–12:45, Theater

Quantum-criticality in two-dimensional transverse-field Ising models with frustrated long-range interactions — •Sebastian Fey, Sebastian C. Kapfer, and Kai P. Schmidt — FAU Erlangen-Nürnberg, Germany

Quantum-critical behavior is found in many quantum systems displaying universal properties such as critical exponents. In the past, most investigations of strongly correlated quantum many-body systems have tackled short-range interactions because long-range interacting systems are notoriously difficult to treat. Nevertheless, important examples of long-range interactions exist in nature, e.g. dipolar interactions in spin ice or long-range forces between cold atoms in optical lattices. Here, we present results for the frustrated long-range transverse-field Ising model (lrTFIM) with antiferromagnetic interactions on two-dimensional lattices obtained via linked-cluster expansions extended by classical Monte-Carlo integrations. It is found that the nature of the phase transition crucially depends on the lattice geometry: On the square lattice, the lrTFIM remains in the nearest-neighbor universality class for all algebraically-decaying interactions studied. In contrast, on the triangular lattice, the nature of the quantum phase transition changes from 3D XY universality to a first-order transition due to the presence of a stripe-ordered phase for very slowly-decaying Ising interactions.

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