Current-induced perpendicular effective magnetic field in magnetic heterostructures

Abstract

Generation of perpendicular effective magnetic field or perpendicular spins (σz) is central for the development of energy-efficient, scalable, and external-magnetic-field-free spintronic memory and computing technologies. Here, we report the first identification and the profound impacts of a significant effective perpendicular magnetic field that can arise from asymmetric current spreading within magnetic microstrips and Hall bars. This effective perpendicular magnetic field can exhibit all the three characteristics that have been widely assumed in the literature to "signify" the presence of a flow of σz, i.e., external-magnetic-field-free current switching of uniform perpendicular magnetization, a sin2ϕ-dependent contribution in spin-torque ferromagnetic resonance signal of in-plane magnetization (ϕ is the angle of the external magnetic field with respect to the current, and a ϕ-independent but field-dependent contribution in the second harmonic Hall voltage of in-plane magnetization. This finding suggests that it is critical to include current spreading effects in the analyses of various spin polarizations and spin-orbit torques in magnetic heterostructure. Technologically, our results provide perpendicular effective magnetic field induced by asymmetric current spreading as a novel, universally accessible mechanism for efficient, scalable, and external-magnetic-field-free magnetization switching in memory and computing technologies.

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Cited by in corpus (5)

• Switching of Perpendicular Magnetization by Spin-Orbit Torque
• Efficient generation of out-of-plane polarized spin current in polycrystalline heavy metal devices with broken electric symmetries
• Coexistence of unconventional spin Hall effect and antisymmetric planar Hall effect in IrO${}_2$
• Enhancing z spin generation in trivial spin Hall materials for scalable, energy-efficient, field-free, complete spin-orbit torque switching applications
• A Two-Field-Scan Harmonic Hall Voltage Analysis For Fast, Accurate Quantification Of Spin-Orbit Torques In Magnetic Heterostructures