Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 60: [MA] Joint Session "Surface Magnetism II" (jointly with O)

O 60.13: Vortrag

Donnerstag, 29. März 2012, 12:45–13:00, EB 301

Spin transfer torque and Joule heating of field-emitted electrons — •Anika Schlenhoff, Andreas Sonntag, Stefan Krause, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg

Since the detection of the spin polarization of field-emitted electrons in the 1970’s [1], it is an open question which type of effects a high spin-polarized current of field-emitted electrons has onto a magnetic sample. Though spin-polarized two-photon photoemission has gained first insight into the interaction of hot electrons with an underlying spin system [2], the microscopic details still remain to be discovered.

In our studies, we utilize spin-polarized scanning tunneling microscopy (SP-STM) in the field emission mode [3] for the direct observation of the influence of field-emitted electrons onto atomic-scale superparamagnets [4]. The experiments reveal that the injection of high spin-polarized currents via the first field emission resonance (FER) significantly changes the superparamagnet’s switching behavior. Telegraphic noise experiments allow for a detailed current-dependent lifetime analysis, thereby quantifying the spin-transfer torque and Joule heating of the field-emitted electrons. The results are compared to low energy electrons tunneling directly into the nanoisland.

[1] N. Müller et al., Phys. Rev. Lett. 29, 1651 (1972).

[2] A. B. Schmidt et al., Phys. Rev. Lett 105, 197401(2010).

[3] A. Kubetzka et al., Appl. Phys: Lett. 91, 012508 (2007).

[4] S. Krause et al., Phys. Rev. Lett. 103, 127202 (2009).