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MA: Fachverband Magnetismus

MA 21: Frustrated Magnets I

MA 21.5: Vortrag

Mittwoch, 19. März 2025, 10:30–10:45, H18

High-temperature expansion of dynamical spin correlator: Dyn-HTE — •Ruben Burkard¹, Benedikt Schneider^2,3, and Björn Sbierski¹ — ¹Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany — ²Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 Munich, Germany — ³Munich Center for Quantum Science and Technology (MCQST), 80799 Munich, Germany

Currently, there is a scarcity of theoretical methods to calculate dynamical correlation functions at finite temperatures in frustrated spin systems. To address this challenge, we extend the well-established method of high-temperature expansion to the dynamical two-point Matsubara Green’s function, which we calculate to high order in perturbation theory. We consider Heisenberg models with one coupling constant J, arbitrary spin length, and without external magnetic field. We use resummation techniques to extrapolate our results to temperatures down to about T≈ 0.2J. Our method also gives an analytical expression for the frequency dependence, enabling analytical continuation to real frequencies. Using the dynamical information of the Matsubara correlator, we aim to study spin-liquid phases with this approach in the future.

Keywords: high-temperature expansion; dynamical correlation function; Heisenberg model