Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 23: Frustrated Magnets - General

TT 23.11: Vortrag

Mittwoch, 7. September 2022, 17:45–18:00, H22

Interacting magnons in the easy-axis square-lattice XXZ-model and extensions towards ring exchange — •Dag-Björn Hering¹, Matthias R. Walther², Kai P. Schmidt², and Götz S. Uhrig¹ — ¹Technische Universität Dortmund, Department of Physics, Condensed Matter Theory, Otto-Hahn-Str. 4, 44227 Dortmund — ²Friedrich-Alexander-Universität Erlangen-Nürnberg, Institut für Theoretische Physik I, Staudtstraße 7, 91058 Erlangen

The method of non-perturbative continuous similarity transformations (CST) in momentum space captures the physics of the isotropic spin 1/2 antiferromagnetic Heisenberg model on the square lattice (IHM) quantitatively [1-2]. We extend these studies to single- and two-particle properties of models related to the IHM. We start with easy-axis square-lattice XXZ-model as simplemost extension of the IHM. Here, we present and discuss the CST results for the gap [3], the roton mode [4] and the bound-states [3] between the Ising limit to isotropic point in comparison to other methods. In addition, we outline further applications of the CST to models with ring-exchange [5] relevant for cuprates and the J-Q Model as an variant of ring-exchange without frustration [6].

[1] M. Powalski et al., Phys. Rev. Lett. 115, 207202 (2015)

[2] M. Powalski et al., SciPost Phys. 4, 001 (2018)

[3] S. Dusuel et al., Phys. Rev. B 81, 064412 (2010)

[4] R. Verresen et al., Phys. Rev. B 98, 155102 (2018)

[5] K. Majumdar et al., Phys. Rev. B 85, 144420 (2012)

[6] A. W. Sandvik Phys. Rev. Lett. 98, 227202 (2007)