Experimental determination of spin-transfer torque nonadiabaticity parameter and spin polarization in permalloy

S. Lepadatu, M. C. Hickey, A. Potenza, H. Marchetto, T. R. Charlton, S. Langridge, S. S. Dhesi, C. H. Marrows

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

The domain-wall depinning boundary, showing the variation in critical current density with magnetic field, is measured for notched permalloy wires using pulsed-current measurements. The structure of domain walls trapped at the pinning potential provided by the notch is imaged using photoemission electron microscopy. The experimental depinning boundary is compared with those obtained by micromagnetic simulations including the adiabatic and nonadiabatic spin-torque terms. This method allows for the determination of both the nonadiabaticity parameter β and spin current polarization P, which we obtain as β=0.040±0.005 and P=0.40±0.02 at room temperature.

Original languageEnglish
Article number094402
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume79
Issue number9
DOIs
StatePublished - Mar 3 2009
Externally publishedYes

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