SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 50: Focus Session: Superconducting Nickelates II

TT 50.5: Vortrag

Donnerstag, 30. März 2023, 16:00–16:15, HSZ 03

Nature of magnetic coupling in bulk infinite-layer nickelates versus cuprates — •Armin Sahinovic, Benjamin Geisler, and Rossitza Pentcheva — Fakultät für Physik, Universität Duisburg-Essen

In contrast to cuprates, where the proximity of antiferromagnetism (AFM) and superconductivity is well established, first indications for AFM interactions in superconducting infinite-layer nickelates [1] were only recently obtained [2,3]. Here, we explore, based on first-principles simulations, the nature of the magnetic coupling in NdNiO₂ as a function of the on-site Coulomb and exchange interaction, varying the explicit hole doping and the treatment of the Nd 4f electrons. The U-J phase diagrams for undoped nickelates and cuprates indicate G-type ordering, yet show different U dependency. By either Sr hole doping or explicit treatment of the Nd 4f electrons, we find a transition to a Ni C-type AFM ground state. We trace this back to a distinct response of the Ni vs. Cu e_g orbitals to the hole doping. The interaction between Nd 4f and Ni 3d spin stabilizes C-type AFM order on both sublattices. Though spin-orbit interactions induce a band splitting near the Fermi energy, the bad-metal state is retained under epitaxial strain. The magnetocrystalline anisotropy features an in-plane easy axis, related to the planar NiO₂ coordination. These results establish the nickelates as a unique platform to study unconventional superconductivity.
[1] D. Li et al., Nature 572, 624 (2019)
[2] J. Fowlie et al., Nature Physics 18, 1043 (2022)
[3] H. Lu et al., Science 373, 213 (2021)