Magnetism and proximity-induced Rashba effect at Mn-3d bands of asymmetric BaMnO₃|KTaO₃ heterojunction

Rashba-like spin-orbit interaction (SOI) at oxide heterostructures emerges as a much sought-after feature in the context of oxide spintronics and spin-orbitronics. KTaO₃ (KTO) is one of the best substrates available for the purpose, owing to its strong SOI and alternating +1|-1 charged layers along the (001) direction. We visualize the Rashba-like interaction in KTO (001) surface with the help of spin texture plotted directly from density functional theory (DFT) calculations along with the isoenergetic contours, providing a confirmatory test of the presence of only linear Rashba interaction. We use DFT calculations to examine the asymmetric BaMnO₃|KTaO₃ (BMO|KTO) oxide heterostructure where the inequivalent bottom and top interfaces break the inversion symmetry due to their opposite polar discontinuities. We observe Rashba-like splitting for the bands of Mn-3d near the Fermi level of C-type antiferromagnetic (BMO|KTO) owing to the proximity to Ta atoms from the 5d series. We comprehensively analyze Rashba-like SOI with the help of three-dimensional band dispersion, isoenergetic contours, and projected spin textures for Rashba-like Mn-3d bands. Our results reveal reasonably strong linear Rashba interaction in the heterostructure. The rigorous analysis of spin textures of the antiferromagnetic heterostructure presented here may be crucial for future developments in spintronics.