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TT: Fachverband Tiefe Temperaturen

TT 64: BKT Physics

TT 64.6: Vortrag

Mittwoch, 11. März 2026, 18:00–18:15, HSZ/0103

Persistence of the Berezinskii-Kosterlitz-Thouless transition with long-range couplings — •Luis Walther^{1, 2}, Josef Willsher^{1, 3, 2}, and Johannes Knolle^{1, 3, 4} — ¹Technical University of Munich, TUM School of Natural Sciences, Physics Department, 85748 Garching, Germany — ²Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany — ³Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 München, Germany — ⁴Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom

The Berezinskii–Kosterlitz–Thouless (BKT) transition is an archetypal example of a topological phase transition, which is driven by the proliferation of vortices. In this Letter, we analyze the persistence of the BKT transition in the XY model under the influence of long-range algebraically decaying interactions of the form ∼ 1/r^2+σ. The model hosts a magnetized low temperature phase for sufficiently small σ. Crucially, in the presence of long-range interactions, spin waves renormalize the interaction between vortices, which stabilizes the BKT transition. As a result, we find that there is no direct transition from the magnetized to the disordered phase and that the BKT transition persists for arbitrary long-range exponents, which is distinct from previous results. We use both Landau–Peierls-type arguments and renormalization group calculations—including a coupling between spin wave and topological excitations—and obtain similar results. We discuss the relevance of our findings for current Rydberg atom experiments, and highlight the importance of long-range couplings for other spin models.

Keywords: BKT transition; Long-range interactions; Landau Peierls type argument; Long-range Criticality; Spin wave renormalization