Nansocale imaging of antiferromagnetic domains in epitaxial Cr₂O₃ films using diamond quantum sensing microscopy

Magnetic microscopy using nitrogen vacancy (NV) centers in diamond has become a versatile tool to study magnetic phenomena at the nanoscale [1]. In this study we use NV microscopy to map magnetic domains in antiferromagnetic (AFM) epitaxial Cr₂O₃ films. Cr₂O₃ thin films have been used to realize voltage-controlled AFM spintronics utilizing the peculiar boundary magnetization of single domains [2]. Boron doping can increase the Néel temperature of Cr₂O₃ to above 400 K and allow Voltage controlled Néel vector 90⁰-rotation in zero magnetic field [3]. We present a detailed investigation of magnetic domains configuration in pure 200-nm thick Cr₂O₃ grown via pulsed laser deposition on Al₂O₃. Our study shows unique magnetic-domain structures similar to the granular Cr₂O₃ films [4]. We perform magnetic-field cooling measurements (heating above Néel temperature, then cooling under an applied field > 0.4 T) and measure the new magnetic domain configuration. We discuss plans to measure the dynamic domain wall evolution on voltage-induced domain reversal in pure and B doped films. [1] F. Casola, et al., Nat. Rev. Mat. 3, 17088 (2018). [2] N. Wu, et al., Phys. Rev. Lett. 106, 087202 (2011). [3] A. Mahmood, et al. Nat. Comms. 12, 1674 (2021). [4] P. Appel, et al., Nano Lett. 19, 1682 (2019).