Berlin 2024 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 52: Nickelates II
TT 52.1: Invited Talk
Wednesday, March 20, 2024, 15:00–15:30, H 3010
A tale of two kinds of superconducting nickelates — •Frank Lechermann — Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum, Germany
Layered nickelates have been of interest since the early days of high-Tc superconducting (SC) cuprates as possible additional representants of unconventional superconductors. But only in 2019, a stable SC phase has been identified in thin-films of Sr-doped NdNiO2 with a Tc∼ 20 K [1]. Further SC members from this class of low-valence nickelates have been spotted afterwards. And just when the debate about the similarity between SC cuprates and nickelates, both with akin 3d9−x formal transition-metal valence, was at its zenith, a SC bilayer nickelate of formal 3d8−x valence was detected at high pressure with Tc∼ 80 K in spring 2023 [2]. Interestingly, according to our theoretical investigations [3,4] all these SC nickelates have a multiorbital Ni-eg flat-band scenario in common.
In this talk, it will be shown that an advanced combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) provides unique access to this novel playground of high-Tc nickelate superconductivity. Albeit the whole field is still at its infancy, the multiorbital regime together with the SC properties at distinctly different 3d electron count renders obvious that many further surprises may be uncovered in the future.
[1] D. Li et al., Nature 572 (2019) 624
[2] H. Sun et al., Nature 621 (2023) 493
[3] F. Lechermann, Phys. Rev. X 10 (2020) 041002
[4] F. Lechermann et al., arXiv:2306.05121 (2023)
Keywords: transition-metal oxides; dynamical mean-field theory; density functional theory; strong correlations; unconventional superconductivity