Magnetic and f-electron effects in LaNiO2 and NdNiO2 nickelates with cuprate-like $$3{d}_{{x}^{2}-{y}^{2}}$$ band

Abstract

Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally. The low-energy electronic structure of the parent compound NdNiO2, the role of electronic correlations in driving superconductivity, and the possible relationship between the cuprates and the nickelates are still open questions. Here, by comparing LaNiO2 and NdNiO2 systematically within a parameter-free, all-electron first-principles density-functional theory framework, we reveal the role of Nd 4f electrons in shaping the ground state of pristine NdNiO2. Strong similarities are found between the electronic structures of LaNiO2 and NdNiO2, except for the effects of the 4f electrons. Hybridization between the Nd 4f and Ni 3d orbitals is shown to significantly modify the Fermi surfaces of various magnetic states. In contrast, the competition between the magnetically ordered phases depends mainly on the gaps in the Ni $$3{d}_{{x}^{2}-{y}^{2}}$$ 3 d x 2 − y 2 band. Our estimated value of the on-site Hubbard U in the nickelates is similar to that in the cuprates, but the value of the Hund’s coupling JH is found to be sensitive to the Nd magnetic moment. In contrast with the cuprates, NdNiO2 presents 3D magnetism with competing antiferromagnetic and (interlayer) ferromagnetic exchange, which may explain why the Tc is lower in the nickelates.

Low Valence Nickelates: Launching the Nickel Age of Superconductivity

“…Neél type order is consistently obtained in DFT studies [24, 27, 29, and 51], as in d 9 insulating cuprates. The predicted AFM ground state in DFT + U calculations [64] is characterized by the involvement of both d x 2 −y 2 and d z 2 Ni bands [65]. This state is peculiar in that it displays a flat-band one-dimensional-like van Hove singularity of d z 2 character pinned at the Fermi level.…”

Dynamical Mean Field Studies of Infinite Layer Nickelates: Physics Results and Methodological Implications

“…Theoretically a number of DFT + U, hybrid DFT and DFT + DMFT studies have studied magnetism of infinite layer nickelates [17,21,24,25,84,99,101,108,111] and reported a wide range of magnetic superexchange [17,18,23,66,76,77,99,112] from a small value of about 10 meV [23,99] to an intermediate value of about 30 meV [66] to a large value of about 80-100 meV [17,18,76,77,112]. DFT + DMFT studies have not examined the Ni 13 MLWF 2 U = 7, J = 0.7 290 7.6 [44] 13 SLWF 2 U = 7, J = 0.7 290 3.9 [117] 16 MLWF (Ni, Nd, O) 5 U avg = 6, J avg = 0.95 290 3 [44] Projectors −10 to 3 2 U = 7, J = 0.7 290 5.6 [108] Projectors −10 to 3 5 U avg = 10, J avg = 1 30 6.4 [108] Projectors −10 to 3 5 U avg = 10, J avg = 1 (SIC on O) 30 Mott insulating [44] Projectors −10 to 10 2 U = 7, J = 0.7 290 4.6 [27] Projectors −10 to 10 5 U avg = 7, J avg = 0.7 390 3.7 [16] Projectors −10 to 10 5 U avg = 5, J avg = 1 100 2.8 [101] Projectors −10 to 10 5 U avg = 5, J avg = 0.8 -2.4 [101] Projectors −10 to 10 5 U avg = 9, J avg = 0.8 -4.1 [15] Projectors −10 to 10 exchange coupling systematically.…”

Low Valence Nickelates: Launching the Nickel Age of Superconductivity

“…Neél type order is consistently obtained in DFT studies 24,27,29,51 , as in d 9 insulating cuprates. The predicted AFM ground state in DFT+U calculations 61 is characterized by the involvement of both d x 2 −y 2 and d z 2 Ni bands 62 . This state is peculiar in that it displays a flat-band one-dimensional-like van Hove singularity of d z 2 character pinned at the Fermi level.…”