Current-induced switching of thin film α−Fe2O3 devices imaged using a scanning single-spin microscope

Electrical switching of N\'eel order in an antiferromagnetic insulator is desirable as a basis for memory applications. Unlike electrically driven switching of ferromagnetic order via spin-orbit torques, electrical switching of antiferromagnetic order remains poorly understood. Here we investigate the low-field magnetic properties of 30-nm-thick, $c$-axis-oriented $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ Hall devices using a diamond nitrogen-vacancy center scanning microscope. Using the canted moment of $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ as a magnetic handle on its N\'eel vector, we apply a saturating in-plane magnetic field to create a known initial state before letting the state relax in low field for magnetic imaging. We repeat this procedure for different in-plane orientations of the initialization field. We find that the magnetic field images are characterized by stronger magnetic textures for fields along $[\overline{1}\overline{1}20]$ and $[11\overline{2}0]$, suggesting that despite the expected 3-fold magnetocrystalline anisotropy, our $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ thin films have an overall in-plane uniaxial anisotropy. We also study current-induced switching of the magnetic order in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$. We find that the fraction of the device that switches depends on the current pulse duration, amplitude, and direction relative to the initialization field.