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A. Killinger

Publications and source records attributed to A. Killinger.

2 recordsLinked to original sources
arXiv2003

Dynamics of ferromagnetic nanomagnets with vortex or single-domain configuration

We study the dynamics of flat circular permalloy nanomagnets for 1.) magnetic vortex and 2.) single-domain configurations, using micromagnetic simulation. Dynamical studies for isolated vortex structures show that both the vorticity and the central polarity of the out-of-plane component can be switched fast (50-100 ps) and independently. Micromagnetic simulations of the switching process in thin cylindrical Permalloy (Py) nanoparticles with an initial stable single-domain state show nearly homogeneous single-domain behaviour followed by excitation of spin waves.

cond-mat.mtrl-sci↗
arXiv2002

Statics and Fast Dynamics of Nanomagnets with Vortex Structure

Within the framework of the Landau-Lifshitz-Gilbert equation, using permalloy parameters, we study the statics and dynamics of flat circular magnetic nano-structures with an in-plane magnetic vortex configuration, putting particular emphasis on the (planar) vorticity of the magnetic state and on the (perpendicular) polarisation of the vortex center (which may be shifted with respect to the center of the circle). These binary degrees of freedom can in principle be used to manipulate two independent bits of information. Studying switching processes induced by in-plane and out-of plane field pulses we find that it is possible to switch the vorticity of the magnetic dot on a time scale of 40 ps in strong enough and short enough perpendicular external field pulses (B_z^ext \approx 0.5 T, duration \approx 40 ps). But for realistically small values of the Gilbert damping, only the vorticity can be switched this fast, and it turns out that it is better to dismiss the center of the circle totally, concentrating on flat 'nano-rings' with an inner radius R_1 and an outer radius R_2. On these 'nano-rings' the vortex state is more stable, and with respect to the switching of the vorticity these structures have similar properties as circular dots.

cond-mat.mtrl-sci↗