Vortex-antivortex proliferation from an obstacle in thin film ferromagnets
Artikel i vetenskaplig tidskrift, 2017

Magnetization dynamics in thin film ferromagnets can be studied using a dispersive hydrodynamic formulation. The equations describing the magnetodynamics map to a compressible fluid with broken Galilean invariance parametrized by the longitudinal spin density and a magnetic analog of the fluid velocity that define spindensity waves. A direct consequence of these equations is the determination of a magnetic Mach number. Micromagnetic simulations reveal nucleation of nonlinear structures from an impenetrable object realized by an applied magnetic field spot or a defect. In this work, micromagnetic simulations demonstrate vortex-antivortex pair nucleation from an obstacle. Their interaction establishes either ordered or irregular vortex-antivortex complexes. Furthermore, when the magnetic Mach number exceeds unity (supersonic flow), a Mach cone and periodic wavefronts are observed, which can be well-described by solutions of the steady, linearized equations. These results are reminiscent of theoretical and experimental observations in Bose-Einstein condensates, and further support the analogy between the magnetodynamics of a thin film ferromagnet and compressible fluids. The nucleation of nonlinear structures and vortex-antivortex complexes using this approach enables the study of their interactions and effects on the stability of spin-density waves.

dynamics

waves

nucleation

skyrmions

motion

magnetic droplet solitons

Författare

Ezio Iacocca

Chalmers, Fysik, Teoretisk fysik

M. A. Hoefer

University of Colorado at Boulder

Physical Review B

24699950 (ISSN) 24699969 (eISSN)

Vol. 95 134409

Styrkeområden

Livsvetenskaper och teknik

Ämneskategorier

Strömningsmekanik och akustik

Den kondenserade materiens fysik

DOI

10.1103/PhysRevB.95.134409