Dresden 2011 – scientific programme

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MA: Fachverband Magnetismus

MA 49: Spin-dependent Transport/ Spin Torque

MA 49.6: Talk

Thursday, March 17, 2011, 12:00–12:15, HSZ 04

A direct approach to measure the nonadiabatic spin transfer torque parameter — •Ming Yan¹ and Riccardo Hertel^1,2 — ¹Institut für Festkörperforschung, Elektronische Eigenschaften, Forschungszentrum Jülich GmbH — ²Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504

The nonadiabatic spin transfer torque parameter β plays an important role in spin dynamics driven by electric current. Measuring β is however usually difficult due to the entanglement of β with the spin polarization rate P. Although various methods to extract the value of β have been suggested, a direct measurement which does not require a model-dependent comparison with numerical simulations is to date elusive. The recently reported dynamic properties of transverse domain-walls in thin cylindrical nanowires [1] provide an approach to measure P and β directly and independently. Driven by a magnetic field or/and an electric current, this type of domain wall precesses around the wire while propagating along the wire. Measuring the linear velocity of the domain wall driven by an electric current allows a direct determination of P. The precessional frequency of the domain wall is proportional to β. The value of β can be unambiguously determined by measuring the frequency shifts caused by electric currents from the Larmor precession of the domain wall. An excellent agreement is achieved between analytical calculations and micromagnetic simulations.
M. Yan, A. Kákay, S. Gliga, and R. Hertel, Phys. Rev. Lett. 104, 057201 (2010).