Accurate analysis of harmonic Hall voltage measurement for spin–orbit torques
Source abstract
Abstract
An accurate method is developed to extract the spin–orbit (SO) effective fields by analyzing harmonic Hall voltage measurements and deriving detailed analytical equations that consider both the z component of the applied magnetic field and the second-order perpendicular magnetic anisotropy. The method is tested by analyzing the results of a macrospin simulation. The SO effective fields that are extracted from the analysis are consistent with the input SO effective fields that are used in the macrospin simulation over the entire range of the polar magnetization angle and for a wide range (0–2) of the ratio of the planar to the anomalous Hall voltage considered in this study. The accuracy of the proposed method is demonstrated via a systematic study that involves comparing its results with those of a conventional analytical method. A way to extract information about complex spin–orbit interactions from simple voltage measurements has been developed by a team in Korea. Recent research has shown that a current can switch the direction of electron spins in a ferromagnet when a ferromagnetic layer is placed on a non-magnetic one. This phenomenon is driven by the so-called spin-orbit torque, but its underlying mechanisms are unclear. The framework developed by Sang Ho Lim and co-workers from Korea University obtains information about these spin-orbit fields from simple measurements of the harmonic Hall voltage. Their analytical equations could improve the understanding of magnetization switching in magnetic materials since, unlike earlier equations, they include both the magnetic field applied perpendicular to the films and the second-order perpendicular magnetic anisotropy. An accurate method, with detailed analytical equations, is developed to extract the spin–orbit (SO) effective fields through analysis of the results of harmonic Hall voltage measurements. Both the z component of the applied magnetic field (its directions, together with the axes and the Hall bars, are shown in the left figures) and the second-order perpendicular magnetic anisotropy are taken into account. The contour plots (right figures) showing the deviation (in %) from input values of the damping-like (ΔHDL) and field-like (ΔHFL) SO effective fields clearly demonstrate a significant improvement in the accuracy of the results obtained from the new refined method.
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Research context
OpenAlex topics: Magnetic Field Sensors Techniques · Magnetic properties of thin films · Magnetic Properties and Applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (35)
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