Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 35: Focused Session: Charge and Spin Transport through Junctions at the Nanometre Scale

TT 35.5: Topical Talk

Thursday, March 29, 2012, 12:20–13:00, H 0104

Spin-current manipulation of atomic-scale magnets using SP-STM — •Stefan Krause — Institute of Applied Physics, University of Hamburg, Germany

A prerequisite on the way to advanced applications in spintronics is the detailed understanding of current-induced magnetization switching (CIMS). Here, the spin-transfer torque generated by a spin current forces a magnet to reverse its magnetization. Spin-polarized scanning tunneling microscopy (SP-STM) provides an ideal representation of a tunneling magneto-resistance device, with vacuum serving as the tunnel barrier between a biased magnetic tip and a magnetic sample.

In our experiments the ultimate lateral resolution of SP-STM is used for a very local observation and manipulation of individual Fe/W(110) nanoislands in the superparamagnetic regime. Performing a current-dependent lifetime analysis of the magnetic states, three fundamental contributions to CIMS are clearly separated and quantified: spin-transfer torque, Joule heating and Oersted field [1,2].

Lowering the temperature leads to a stabilization of the nanomagnets. In this regime the high spin-polarized tunnel current solely triggers magnetization reversal, and the threshold is determined by ramping the tunnel current. For fast reversal, short high-current pulses are applied, thereby demonstrating the capability of SP-STM for the reliable manipulation of magnetism on the atomic scale[3].

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

[2] S. Krause et al., Phys. Rev. Lett. 107, 186601 (2011).

[3] G. Herzog et al., Appl. Phys. Lett. 96, 102505 (2010).