AVS 56th International Symposium & Exhibition
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI+EM-WeA

Paper MI+EM-WeA12
Enhancement of Spin Injection Efficiency by Interface Modification for Fe and Fe31Co69 Thin Films on GaAs(001)

Wednesday, November 11, 2009, 5:40 pm, Room C1

Session: Magnetism and Spin Injection in Semiconductors
Presenter: S.F. Alvarado, IBM Zurich Research Laboratory, Switzerland
Authors: S.F. Alvarado, IBM Zurich Research Laboratory, Switzerland
G. Salis, IBM Zurich Research Laboratory, Switzerland
A. Fuhrer, IBM Zurich Research Laboratory, Switzerland
L. Gros, IBM Zurich Research Laboratory, Switzerland
R.R. Schlittler, IBM Zurich Research Laboratory, Switzerland
Correspondent: Click to Email
We report on a detailed study of the influence of ferromagnet/semiconductor interface modifications on the electrical spin injection efficiency of Fe and Fe31Co69 thin film electrodes into the GaAs(001) surface. These modifications are induced by: a) Varying the As/Ga surface concentration of GaAs(001); and b) Post-growth annealing of the ferromagnetic thin films. Electrical spin injection experiments are carried out in a non-local device geometry at temperatures between 2.5 and 300 K. Devices were fabricated by means of either optical, e-beam, or nanostencil lithography. Non-local spin signals in the range of 2V/A at a temperature of 5K have been detected between two strip electrodes, one 2 and the other 6 μm in width, 60 μm long, separated 3 μm from each other. The spin-polarization characteristics of the devices are observed to strongly depend on substrate surface preparation and annealing treatment of the metal/semiconductor devices. The latter has a very strong influence on the magnitude of the non-local spin polarization signal, which we observe to increase by about two orders of magnitude after annealing steps from 120 °C up to 290 °C.