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DY: Fachverband Dynamik und Statistische Physik

DY 29: Poster: Quantum Dynamics and Many-body Systems

DY 29.3: Poster

Mittwoch, 19. März 2025, 15:00–18:00, P4

Dynamics of topological defects in non-equilibrium magnon condensates — •Alexander Wowchik and Achim Rosch — Institut für Theoretische Physik, Universität zu Köln, 50937 Cologne, Germany

It has been demonstrated in the past that thin Yttrium Iron Garnet (YIG) films exhibit condensation of magnons in two degenerate minima of the band structure when driven with microwave radiation in the presence of an external magnetic field.

This creates a non-equilibrium many-body system at room temperature, which provides a framework to study the dynamics of self-propelling units that violate the conservation of energy, analogous to models of active matter.

We examine the behaviour of a single topological vortex defect in the magnon condensate after explicitly breaking the spatial inversion symmetry that restricts the dynamics of the ideal system. This is motivated by an asymmetric configuration in the typical experimental setup.

The study is performed by solving the driven-dissipative Gross-Pitaevskii equation for the emergent condensate degrees of freedom. It is derived from the semi-classical limit of an effective U(1) x O(2) symmetric Keldysh field theory.

The results are compared to micromagnetic simulations of the underlying ferromagnetic spin-Hamiltonian.

Keywords: Magnon condensate; Non-equilibrium; Topological defects; Gross-Pitaevskii equation; Field theory