Rashba spin-orbit coupling in infinite-layer nickelate films on SrTiO3(001) and KTaO3(001)

Abstract

The impact of spin-orbit interactions in NdNiO2/SrTiO3(001) and NdNiO2/KTaO3(001) is explored by performing density functional theory simulations including a Coulomb repulsion term. Polarity mismatch drives the emergence of an interfacial two-dimensional electron gas in NdNiO2/KTaO3(001) involving the occupation of Ta 5d conduction-band states, which is twice as pronounced as in NdNiO2/SrTiO3(001). We identify a significant anisotropic k3 Rashba spin splitting of the respective dxy states in both systems that results from the broken inversion symmetry at the nickelate-substrate interface and exceeds the width of the superconducting gap. In NdNiO2/KTaO3(001), the splitting reaches 210 meV, which is comparable to Bi(111) surface states. At the surface, the Ni 3dx2−y2-derived states exhibit an unexpectedly strong linear Rashba effect with αR∼125 meV Å, exemplifying its orbital selectivity. The corresponding Fermi sheets present a reconstructed circular shape due to the electrostatic doping, but undergo a Lifshitz transition towards a cupratelike topology deeper in the film that coincides with a realignment of their spin texture. These results promote surface and interface polarity as interesting design parameters to control spin-orbit physics as well as the superconducting pairing in infinite-layer nickelate heterostructures.

Source-reported materials — not catalogue approval

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