Rashba splitting in infinite-layer nickelate heterostructures*

We explore the impact of spin-orbit interactions in infinite-layer NdNiO₂/SrTiO₃(001) and NdNiO₂/KTaO₃(001) film geometries by performing density functional theory simulations including a Coulomb repulsion term. Polarity mismatch drives the emergence of an interfacial two-dimensional electron gas (2DEG) in the KTaO₃ system due to the occupation of Ta 3d states, which we find to be twice as pronounced as in the SrTiO₃ case [1-3]. This phenomenon is accompanied by sizable ferroelectric-like displacements of the B-site cations in the substrate. We identify a significant Rashba splitting of the corresponding electronic states resulting from the broken inversion symmetry and the strongly asymmetric electrostatic potential at the nickelate-substrate interface. Comparison of the two distinct substrates provides insight into the role of the structural asymmetry and the atomic number of the involved elements. The results suggest these and related heterostructures as interesting platforms to investigate the coupling of the recently discovered nickelate superconductors [4] to a Rashba-split correlated 2DEG.

[1] B. Geisler and R. Pentcheva, Phys. Rev. B 102, 020502(R) (2020)

[2] B. Geisler and R. Pentcheva, Phys. Rev. Research 3, 013261 (2021)

[3] B. H. Goodge et al., arXiv:2201.03613 [cond-mat.supr-con]

[4] D. Li et al., Nature 572, 624 (2019)