Speaker
Description
The discovery of superconductivity in hole-doped infinite-layer NdNiO$_2$ — a transition metal oxide that is both isostructural and isoelectronic to cuprate superconductors — has lead to renewed enthusiasm in the hope of understanding the origin of unconventional superconductivity. In this talk, we present the many body wavefunction analysis of electron-removal (which mimics hole-doping) states in infinite-layered NdNiO$_2$ and CaCuO$_2$ obtained from the state-of-the-art many-body multireference quantum chemistry calculations. We find that the hole-doped ground state of NdNiO$_2$ is very different from the isostructural cuprate analog CaCuO$_2$ [1], although the ground states of the parent undoped compounds are for the most part identical [2]. The doped hole in NdNiO$_2$ is mainly localized on the Ni 3$d_{x^2−y^2}$ orbital to form a closed-shell singlet, and this singlet configuration contributes to ~40% of the wavefunction. In contrast, in CaCuO$_2$ the Zhang-Rice singlet configurations contribute to ~65% of the wavefunction. The dynamic radial-type correlations within the Ni d-manifold are significantly stronger in NdNiO$_2$ compared to the cuprate, as a result, the multiplet effects become crucial. Further, the additional hole foot-print is more three dimensional in NdNiO$_2$. We conclude that the most commonly used three-band Hubbard model employed to express the doped scenario in cuprates represents ~90% of the wavefunction for CaCuO$_2$, but such a model grossly approximates the wavefunction for NdNiO$_2$ as it only stands for ~60% of the wavefunction.
[1] Vamshi M. Katukuri, et al. arXiv:2201.05495
[2] Vamshi M. Katukuri, et al. Phys. Rev. B 102, 241112(R)
