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MA: Fachverband Magnetismus

MA 29: Skyrmions II

MA 29.3: Vortrag

Mittwoch, 19. März 2025, 15:30–15:45, H20

Quantum skyrmions and antiskyrmions in monoaxial chiral magnets — •Štefan Liščák, Andreas Haller, Andreas Michels, Thomas L. Schmidt, and Vladyslav Kuchkin — Department of Physics and Materials Science, University of Luxembourg

Classical monoaxial chiral magnets represent a unique magnetic system that allows for the stabilization of both skyrmions and antiskyrmions of equal energy. Unlike a similar situation in frustrated magnets, the energy landscape here is much simpler, consisting of four states: the saturated ferromagnetic state, spin-spiral, skyrmion, and antiskyrmion. This simplicity makes such systems interesting for potential applications that rely on manipulating these states. We study the quantum analog of the already established classical theory by investigating the low-excitation spectra of a spin-1/2 quantum Heisenberg model with monoaxial Dzyaloshinskii-Moriya interaction. We establish that such a model supports the existence of skyrmion and antiskyrmion states of equal energy using the density matrix renormalization group method (DMRG). This degeneracy allows for the existence of a mesoscopic Schrödinger cat state exhibiting properties of both skyrmion and antiskyrmion. To characterize this superposition, we calculate two-point correlation functions, which can be measured in neutron scattering experiments. Finally, we introduce a perturbation in the form of a magnetic field gradient to induce a non-trivial time evolution of the superposition state. We study this time evolution both using a numerical variational approach and the collective coordinates method.

Keywords: Monoaxial Chiral Magnet; Quantum Skyrmions; Density Matrix Renormalization Group; Small-Angle Neutron Scattering