Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 68: Poster 5

MA 68.26: Poster

Friday, March 24, 2017, 09:30–13:00, P2-OG4

Magnetic vortex core pinning and its influence on core gyration detection by STM — •Marvin Knol — II. Physikalisches Institut B, RWTH Aachen University

A magnetic vortex is the simplest non-trivial magnetic order of thin magnetic platelets with low magnetic anisotropy. The center of this chiral magnetic structure features an out of plane magnetic moment called the vortex core. We use external magnetic fields to manipulate the core within Fe islands prepared in UHV on W(110) probing it via spin polarized STM [1]. As expected, the vortex core is squeezed by an oppositely oriented out-of-plane field up to 1.6 T and shifted by an in-plane field. Moreover, we find Barkhausen like jumps [2] in the magnetization during in-plane field sweeps when the vortex core is additionally squeezed by an out-of-plane field. We attribute the jumps to pinning most likely at remaining surface adsorbates.

Micromagnetic simulations [3] reveal that the vortex core gyration is only excitable by spin polarized STM, if a resonant high frequency current is applied to a tip of canted magnetization with respect to the vortex core and the core is additionally squeezed. Thus, overcoming the pinning of the squeezed core is mandatory for dynamic experiments.

[1] A. Wachowiak et al., Science 298, 577*580 (2002)

[2] R. L. Compton et al., Phys. Rev. Lett. 97, 137202 (2006)

[3] A. Vansteenkiste et al., AIP Adv. 4, 107133 (2014)