Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 22: Spin Dynamics / Spin Torque III

MA 22.2: Vortrag

Donnerstag, 25. März 2010, 10:00–10:15, H10

Critical Current for Switching the Magnetization of Quasistable Nano-Islands Using SP-STM — •Stefan Krause, Gabriela Herzog, Anika Emmenegger, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Germany

Spin-polarized scanning tunneling microscopy (SP-STM) has been demonstrated to be capable for manipulating the superparamagnetic switching behavior of nano-islands, using the spin torque and Joule heating of elevated spin-polarized tunnel currents [1]. The question arises whether SP-STM can also be used to manipulate static magnetic nanostructures, thereby opening perspectives for future data storage technologies based on SP-STM.

In our experiment, an individual thermally quasistable nano-island consisting of about 40 iron atoms on a W(110) surface has been addressed using a magnetic probe tip. Sweeping the spin-polarized tunnel current between tip and sample from the nA to the µA regime allows for switching the island’s magnetization back and forth, depending on the bias polarity. The critical current for switching the magnetization back and forth is discussed in terms of the current sweep rate, and numerical simulations supporting the experimental findings are presented. The local current density necessary for switching the magnetization is found to be comparable to that used in experiments on nanopillar devices [2].

[1] S. Krause et al., Science 317, 1537 (2007).

[2] G. D. Fuchs et al., Appl. Phys. Lett. 85, 1205 (2004).