Spin-Transfer Torques Generated by the Anomalous Hall Effect and Anisotropic Magnetoresistance
نویسندگان
چکیده
Spin-orbit coupling in ferromagnets gives rise to the anomalous Hall effect and the anisotropic magnetoresistance, both of which can be used to create spin-transfer torques in a similar manner as the spin Hall effect. In this paper, we show how these effects can be used to reliably switch perpendicularly magnetized layers and to move domain walls. A drift-diffusion treatment of the anomalous Hall effect and the anisotropic magnetoresistance describes the spin currents that flow in directions perpendicular to the electric field. In systems with two ferromagnetic layers separated by a spacer layer, an in-plane electric field causes spin currents to be injected from one layer into the other, creating spin-transfer torques. Unlike the related spin Hall effect in nonmagnetic materials, the anomalous Hall effect and the anisotropic magnetoresistance allow control of the orientation of the injected spins, and hence torques, by changing the direction of the magnetization in the injecting layer. The torques on one layer show a rich angular dependence as a function of the orientation of the magnetization in the other layer. The control of the torques afforded by changing the orientation of the magnetization in a fixed layer makes it possible to reliably switch a perpendicularly magnetized free layer. Our calculated critical current densities for a representative CoFe/Cu/FePt structure show that the switching can be efficient for appropriate material choices. Similarly, control of the magnetization direction can drive domain-wall motion, as shown for NiFe/Cu/NiFe structures.
منابع مشابه
Theory of spin Hall magnetoresistance (SMR) and related phenomena.
We review the so-called spin Hall magnetoresistance (SMR) in bilayers of a magnetic insulator and a metal, in which spin currents are generated in the normal metal by the spin Hall effect. The associated angular momentum transfer to the ferromagnetic layer and thereby the electrical resistance is modulated by the angle between the applied current and the magnetization direction. The SMR provide...
متن کاملخواص ترابردی مغناطیسی واثر هال در نمونه هایGdpr-123
Single phase polycrystalline Gd1-xPrxBa2Cu3O7-δ samples with x=0.05 , 0.10, and 0.15 have been prepared by standard solid state reaction technique and characterized by XRD and SEM analysis. The electrical resistivity, Hall effect and magnetoresistance measurements have been on the samples. The electrical resistivity measurements indicate a reduction of transition temperature (Tc) and an incre...
متن کاملSymmetry and magnitude of spin-orbit torques in ferromagnetic heterostructures.
Recent demonstrations of magnetization switching induced by in-plane current injection in heavy metal/ferromagnetic heterostructures have drawn increasing attention to spin torques based on orbital-to-spin momentum transfer. The symmetry, magnitude and origin of spin-orbit torques (SOTs), however, remain a matter of debate. Here we report on the three-dimensional vector measurement of SOTs in A...
متن کاملMagnetoresistance in inhomogeneous graphene/metal hybrids
Related Articles Anomalous magnetoresistance and magnetocaloric properties of NdRu2Ge2 Appl. Phys. Lett. 102, 062406 (2013) Size effects in thin gold films: Discrimination between electron-surface and electron-grain boundary scattering by measuring the Hall effect at 4K Appl. Phys. Lett. 102, 051608 (2013) Peculiarity of magnetoresistance in high pressure annealed Ni43Mn41Co5Sn11 alloy Appl. Ph...
متن کاملGalvanomagnetic and thermogalvanomagnetic transport effects in ferromagnetic fcc CoxPd1−x alloys from first principles
The galvanomagnetic and thermogalvanomagnetic transport of the prototypical ferromagnetic transition-metal alloy system fcc CoxPd1−x has been investigated on the basis of Kubo’s linear response formalism. The results for the full electric conductivity tensor allow discussing the spin-orbit-induced anisotropic magnetoresistance and the anomalous Hall effect. These are complemented by results for...
متن کامل