Daily Overview: This post sorts papers by relevance to nickelate superconductors. Summaries are AI-generated and may contain errors. arXiv submission processing window: times are unavailable (UTC).
1. $3d_{z^2}$ orbital delocalization and magnetic collapse in superconducting (La,Pr)$_3$Ni$_2$O$_{7-δ}$ films
- Relevance Score:
5.6451 - Authors: Xiaoyang Chen, Wenliang Zhang, Fei Peng, Ting Cui, Guangdi Zhou, Zezhong Li, Jaewon Choi, Lizhi Xu, Yiu-Fung Chiu, Stefano Agrestini, Sahil Tippireddy, Haoliang Huang, Heng Wang, Xianfeng Wu, Peng Li, Jin-Feng Jia, Mirian Garcia-Fernandez, Yi Lu, Er-Jia Guo, Qi-Kun Xue, Zhuoyu Chen, Donglai Feng, Ke-Jin Zhou
- Link: http://arxiv.org/abs/2604.21899v2
- Paper page: 3dz2 orbital delocalization and magnetic collapse in superconducting (La,Pr)₃Ni₂O₇-δ films
Summary: This study utilized X-ray absorption spectroscopy and resonant inelastic X-ray scattering to independently control the strain and oxygen content of (La,Pr)₃Ni₂O₇₋δ thin films, tracking the microscopic evolution from a non-superconducting parent phase to a superconducting phase. The results demonstrate that both tuning methods induce delocalization of the oxygen 2p_z and nickel 3d_z² orbitals, as evidenced by spectral weight transfer from the “upper Hubbard” peak to the hole peak in the O K-edge absorption spectra, accompanied by broadening and weakening of the Ni L-edge absorption spectra and dd excitations. Concurrently, the intensity and correlation length of the long-range spin density wave (SDW) order are significantly suppressed, indicating direct competition with superconductivity; while short-range magnons are damped, their bandwidth remains unchanged. This suggests that the delocalization of oxygen 2p_z and nickel 3d_z² orbitals, along with the robustness of short-range magnons during the melting of the SDW order, are prerequisites for achieving superconductivity, thus providing constraints for theoretical models and pointing toward an orbital-selective pathway for designing nickel-based superconductors.
2. Pairing mechanism and superconductivity in 1313 phase La$_3$Ni$_2$O$_7$
- Relevance Score:
5.3451 - Authors: Cui-Qun Chen, Ming Zhang, Fan Yang, Dao-Xin Yao
- Link: http://arxiv.org/abs/2604.21533v1
- Paper page: Pairing mechanism and superconductivity in 1313 phase La₃Ni₂O₇
Summary: Using density functional theory combined with dynamical mean-field theory (DFT+DMFT) and the random phase approximation (RPA), we systematically investigated the electronic structure and superconducting mechanism of the 1313-phase La₃Ni₂O₇. DMFT calculations reveal that the monolayer subsystem exhibits a nearly insulating state, with the d_{z²} orbital displaying Mott physics, while the trilayer subsystem remains metallic and is primarily responsible for superconductivity, with its Ni-e_g orbitals being hole-doped relative to bulk La₄Ni₃O₁₀. Based on the low-energy effective Hamiltonian derived from DMFT, RPA analysis yields an s^{±}-wave pairing symmetry within the trilayer subsystem. Compared to bulk La₄Ni₃O₁₀, the significantly reduced superconducting transition temperature in the 1313 phase arises from two factors: first, hole doping weakens the pairing strength; second, the monolayer subsystem acts as a weak-link layer, forming S-N-S Josephson junctions between adjacent trilayer superconducting layers, which suppresses interlayer phase coherence and further lowers the global transition temperature. Overall, the high-temperature superconductivity in the Ruddlesden-Popper La₃Ni₂O₇ family should be attributed to the 2222 phase rather than the 1313 phase.