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MA: Fachverband Magnetismus

MA 20: Magnonics II

MA 20.2: Vortrag

Mittwoch, 19. März 2025, 09:45–10:00, H16

Exchange enhanced switching in quantum antiferromagnets with dephasing and relaxation — •Asliddin Khudoyberdiev and Götz S. Uhrig — Condensed Matter Theory, TU Dortmund University, Otto-Hahn-Straße 4, 44221 Dortmund, Germany

One requirement for ultrafast storage devices is that they can be operated in the terahertz (THz) regime. Suitable candidates are antiferromagnets because of their characteristic frequencies range. The efficient control of their order is the focus of a plethora of current studies. Recently, we established a quantum approach, time-dependent Schwinger boson mean-field theory, to reverse the sublattice magnetization in anisotropic quantum antiferromagnets by means of external static and oscillating magnetic fields [1,2]. We also showed that the exchange enhancement for staggered control fields persists on the quantum level so that significantly lower fields are sufficient to switch the order [3]. Our quantum theory incorporates dephasing, i.e., the destructive interference of the contributions of all spin modes at their respective frequencies, which results in a slow, non-exponential decrease of the oscillations after the switching [2,3]. This must be distinguished from spin-lattice relaxation which induces faster decay of oscillations. Our methodological progress including Lindblad dissipators allows us to address the differences between dephasing and spin-lattice relaxation in the switching processes. [1] K. Bolsmann, A. Khudoyberdiev, and G. S. Uhrig, PRX Quantum 4, 030332 (2023) [2] A. Khudoyberdiev and G. S. Uhrig, Phys. Rev. B 109, 174419 (2024) [3] A. Khudoyberdiev and G. S. Uhrig, arXiv:2407.00472.

Keywords: switching in quantum antiferromagnets; exchange enhanced switching; dephasing and relaxation; magnons; Schwinger boson representation