아래와 같이 세미나를 개최하고자 하오니, 관심있는 분들의 많은 참석 부탁드립니다.

The recent discovery of an 80 K superconductor in La₃Ni₂O₇ has attracted considerable interest. While numerous theoretical frameworks have been proposed, most assume that bilayer nickelates reside in the Mott-Hubbard regime. However, recent experiments suggest that La₃Ni₂O₇ may belong to the charge transfer regime.  In the first part of the talk, I present the charge transfer regime of the bilayer nickelates by accounting for doped holes entering the oxygen p orbitals. Interestingly, we show that the Zhang-Rice doublon state emerges as the proper low-energy degrees of freedom for the hole-doped state, distinct from the Zhang-Rice singlet in hole-doped cuprates [3].  The low energy theory in the charge transfer regime is also demonstrated as a bilayer type-II t-J model previously proposed in the Mott- Hubbard regime. Given the richness of this physics, there is a natural desire to simulate the superconductivity using programmable quantum simulators to explore diverse physics phenomena. In the second part of the talk, I present a theoretical proposal to utilize the tetralayer optical lattice systems with ultracold atoms to simulate novel bilayer nickelate superconductors. Notably, the synthetic Kondo interaction simulated in the cold atom system is antiferromagnetic, contrasting with the ferromagnetic Hund coupling inherent in nickelate materials. This difference in the sign of the Kondo interaction enhances the pairing gap, equivalently to Tc allowing us to detour the challenge of reaching ultra-low temperatures in cold atom experimental setups. We further propose a signature to identify the pairing state can be applied to the snapshot measurements.

[1] Hanbit Oh and Ya-Hui Zhang, Phys. Rev. B 108 (2023)

[2] Hui Yang*, Hanbit Oh*, Ya-Hui Zhang, arXiv:2309.15095 (2023)

[2] Hanbit Oh, Boran Zhou, Ya-Hui Zhang, arXiv:2405.00092 (2024)