The discovery of infinite-layer nickelate superconductivity provides a new pathway to realize cuprate analog systems [1]. We first analyzed this compound using a combination of density functional theory and dynamical mean field theory (DFT+DMFT). The results show that the system can be described by a single-band Hubbard model with an additional electron reservoir at least around the superconducting doping region. We then calculated the critical temperature of this simplest model using the dynamical vertex approximation. We obtained a Tc-dome structure centered around 20% Sr-doping [2], which agrees with subsequent experiments. Building on the successful description of the experimental phase diagram, we conducted a comprehensive study of the superconducting instability in the single-band Hubbard model to search for sweet spots for high Tc. Combined with first-principles calculations, we propose that palladates would be a possible alternative to nickelates for optimizing model parameters and achieving a higher Tc in practice [3].
[1] D. Li, K. Lee, B.Y. Wang, M. Osada, S. Crossley, H.R. Lee, Y. Cui, Y. Hikita, H.Y. Hwang, Nature 572, 624–627 (2019).
[2] M. Kitatani, L. Si, O. Janson, R. Arita, Z. Zhong, and K. Held, npj Quantum Mater. 5, 59 (2020).
[3] M. Kitatani, L. Si, P. Worm, J. M. Tomczak, R. Arita, and K. Held, Phys. Rev. Lett. 130, 166002 (2023).
Keywords: unconventional superconductivity, nickelates, palladates, dynamical mean field theory, dynamical vertex approximation