Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 51: Spin Excitations/ Spin Torque
MA 51.5: Vortrag
Freitag, 30. März 2012, 10:30–10:45, H 1012
Determination of the nonadiabatic spin transfer torque parameter via SEMPA investigations — •Stefan Rößler1, Sebastian Hankemeier1, Robert Frömter1, Hans Peter Oepen1, and Benjamin Krüger2 — 1Institute of Applied Physics, Hamburg, Germany — 2I. Institute of Theoretical Physics, Hamburg, Germany
The displacement of a magnetic vortex core in a permalloy rectangle due to an ultrahigh DC current density has been measured utilizing Scanning Electron Microscopy with Polarization Analysis (SEMPA).
A permalloy square of 6 µm x 6 µm x 10 nm size has been prepared on a single crystalline diamond substrate. The ground state for structures of this size is the Landau structure where the magnetization is curling around a sharp vortex core in the middle of the structure. In the center of the core the magnetizaion points out of plane to reduce exchange energy. Thus, each Landau state can be characterized by its sense of rotation c and the direction of the out of plane magnetization p allowing four different states of magnetization. The displacement of the vortex core for three of these different cp-states has been measured up to a DC current density of 7 × 1011 A/m2. As shown in [1] the measurement of three different cp-states allows to separate the effects caused by the oerstedt field, the nonadiabatic, and the adiabatic spin transfer torque. From these measurements the parameter of nonadiabaticity has been determined.
This work is supported by DFG via SFB 668.
References: [1] Krüger et al., Phys. Rev. Lett. 104, 077201 (2010)