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Magnetic-field-induced domain-wall motion in permalloy nanowires with modified Gilbert damping

DOI: 10.1103/PhysRevB.82.094445 DOI Help

Authors: Thomas Moore (Universität Konstanz) , Phillipe Mohrke (University of Konstanz) , Lutz Heyne (University of Konstanz) , Andreas Kaldun (Universität Konstanz) , Mathias Kläui (Universität Konstanz) , Dirk Backes (Paul Scherrer Institut) , Jan Rhensius (Paul Scherrer Institut) , Laura Heyderman (Paul Scherrer Institut) , Jan-ulrich Thiele (Hitachi Global Storage Technology) , Georg Woltersdorf (Universität Regensburg) , Arantxa Rodriguez (Paul Scherrer Institut) , Frithjof Nolting (Paul Scherrer Institut) , Tevfik Mentes (Sincrotrone Trieste) , Miguel Nino (Elettra – Sincrotrone Trieste) , Andrea Locatelli (Elettra – Sincrotrone Trieste) , Alessandro Potenza (Diamond Light Source) , Helder Marchetto (Diamond Light Source) , Stuart Cavill (University of York, Diamond Light Source) , Sarnjeet Dhesi (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 82 (9)

State: Published (Approved)
Published: September 2010

Abstract: Domain wall (DW) depinning and motion in the viscous regime induced by magnetic fields, are investigated in planar permalloy nanowires in which the Gilbert damping is tuned in the range 0.008–0.26 by doping with Ho. Real time, spatially resolved magneto-optic Kerr effect measurements yield depinning field distributions and DW mobilities. Depinning occurs at discrete values of the field which are correlated with different metastable DW states and changed by the doping. For α<0.033, the DW mobilities are smaller than expected while for α>=0.033, there is agreement between the measured DW mobilities and those predicted by the standard one-dimensional model of field-induced DW motion. Micromagnetic simulations indicate that this is because as increases, the DW spin structure becomes increasingly rigid. Only when the damping is large can he DW be approximated as a pointlike quasiparticle that exhibits the simple translational motion predicted in the viscous regime. When the damping is small, the DW spin structure undergoes periodic distortions that lead to a velocity reduction. We therefore show that Ho doping of permalloy nanowires enables engineering of the DW depinning and mobility, as well as the extent of the viscous regime.

Subject Areas: Physics

Instruments: I06-Nanoscience