SOT Enabled 3D Magnetic Field Sensor with Low Offset and High Sensitivity

Abstract

In this work we demonstrate a spin-orbit torque (SOT) magnetic field sensor, designed as a Ta/CoFeB/MgO structure, with high sensitivity and capable of active offset compensation in all three spatial directions. This is described and verified in both experiment and simulation. The measurements of magnetic fields showed an offset of 36, 50, and 37$\hat{\mathrm{I}}¼\mathrm{T}$ for x-, y-, and z-fields. Furthermore, the sensitivities of these measurements had values of 590, 580, and 490$\mathrm{V}{\mathrm{A}}^{-1}{\mathrm{T}}^{-1}$ in the x-, y-, and z-direction. In addition, the robustness to bias fields is demonstrated via experiments and single spin simulations by applying bias fields in y-direction. Cross sensitivities were further analyzed via single spin simulations performing a parameter sweep of different bias fields in the y- and z-direction up to $\pm$1mT. Finally, the extraction of the SOT parameters $\hat{I}{\cdot }_{\mathrm{DL}}$ and $\hat{I}{\cdot }_{\mathrm{FL}}$ is shown via optimization of a single-spin curve to the experimental measurements.

29 pages, 7 figures. To be submitted to Physical Review Applied. Corrected swapped values of SOT parameters. Updated explanation in Section VI "Behavior under bias fields." Added a new appendix section with an additional figure. Made minor edits throughout the manuscript