Regensburg 2013 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 22: Poster II

DF 22.55: Poster

Friday, March 15, 2013, 10:30–13:30, Poster D

Dynamic vortex core reversal studied with micromagnetic simulations — •Hans G. Bauer, Georg Woltersdorf, and Christian H. Back — Universität, Regensburg, Germany

Thin discs of soft magnetic material can have non-trivial ground states of the magnetization. When the demagnetization energy forces the magnetization to lie in the plane of the disc, ground states of curling magnetization (vortex) exist with the magnetization in the middle pointing out-of-plane (vortex core). The ground state is degenerate with respect to the vortex core pointing either up or down (polarity) and the rotation sense of the in-plane magnetization (chirality).

While both are in principle capable of representing a bit in data storage we study two cases of polarity switching, where the vortex core polarity is reversed by a) a short rotating field pulse and b) a combination of sub-GHz and GHz excitations.

First we address the problem of the minimal time required to selectively switch the vortex core with short pulses. In the second study we investigate the threshold amplitude needed for switching at GHz-frequencies when the vortex core is already displaced from its equilibrium position by a low frequency excitation of the vortex, the so-called gyro-frequency. Both results are finally compared to the experimental findings in [1] and [2].

[1] M. Kammerer et al., Phys. Rev. B 86, 134426 (2012)

[2] M. Sproll et al. (to be published)