Paper

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 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. ...

arXiv Daily: nickelate superconductors 2026-04-23

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. Superconductivity in bilayer La$_3$Ni$_2$O$_7$: A review focusing on the strong-coupling Hund’s rule assisted pairing mechanism Relevance Score: 5.3873 Authors: Zhiming Pan, Chen Lu, Fan Yang, Congjun Wu Link: http://arxiv.org/abs/2604.20613v1 Summary: The high-temperature superconductivity in bilayer La₃Ni₂O₇ originates from its unique two-orbital bilayer electronic structure, where the 3d_z² orbital is nearly half-filled and localized, generating strong interlayer antiferromagnetic exchange via the inner apical oxygen 2p_z orbital, while the 3d_x²-y² orbital is approximately quarter-filled and highly itinerant. Under strong coupling, Hund’s rule coupling aligns the spins of the two orbitals on the same nickel site, effectively transferring the interlayer antiferromagnetic exchange to the itinerant 3d_x²-y² orbital, forming an effective coupling J⊥. This mechanism can be simplified into a strong-coupling bilayer t-J-J⊥ model for the 3d_x²-y² band, where J⊥ drives electrons to form interlayer Cooper pairs, realizing extended s-wave pairing superconductivity with high critical temperature. Meanwhile, the strongly localized 3d_z² electrons tend to form interlayer ladder singlets; due to the lack of phase coherence, these singlets do not directly participate in the superconducting condensation but instead give rise to a pseudogap phase. This review systematically elaborates on this strong-coupling Hund’s rule assisted pairing theory, providing a unified framework for understanding the mechanism of high-temperature superconductivity in this system. ...

arXiv Daily: nickelate superconductors 2026-04-22

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. Superconductivity in Ruddlesden-Popper nickelates: a review of recent progress, focusing on thin films Relevance Score: 5.8669 Authors: Yang Zhang, Ling-Fang Lin, Thomas A. Maier, Elbio Dagotto Link: http://arxiv.org/abs/2604.18385v2 Summary: In recent years, significant breakthroughs have been achieved in the study of Ruddlesden-Popper (RP) nickel oxide superconductors. This article systematically reviews the experimental and theoretical progress in this field, with a particular focus on thin-film systems. Key findings include the emergence of superconductivity in bilayer La₃Ni₂O₇ (T_c ~ 80 K) and trilayer La₄Ni₃O₁₀ under high pressure, and, critically, the realization of ambient-pressure superconductivity in ultra-thin films of La₃Ni₂O₇ grown on substrates providing compressive strain—a breakthrough that overcomes the high-pressure limitation and enables the use of experimental techniques previously inaccessible in the superconducting state, such as angle-resolved photoemission spectroscopy (ARPES). On the theoretical side, the system requires simultaneous consideration of both the Ni e_g and a_{1g} orbitals, as well as the strong interlayer coupling within bilayers that gives rise to a “dimer” picture, and exhibits strange metal behavior and strong correlation features reminiscent of cuprates. By comparing the similarities and differences among various RP nickel oxides, this article offers a new perspective on understanding the mechanism of high-temperature superconductivity in correlated electron systems and outlines future research directions. ...

arXiv Daily: nickelate superconductors 2026-04-20

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. Pairing Mechanism in Bilayer Nickelate La$_3$Ni$_2$O$_7$ Superconductors Relevance Score: 5.7408 Authors: Xianxin Wu, Tao Xiang, Jiangping Hu Link: http://arxiv.org/abs/2604.17181v1 Summary: Research on the pairing mechanism of the bilayer nickelate La₃Ni₂O₇ high-temperature superconductor demonstrates that the unified framework based on the “genesis principle” and the “synergistic Fermi surface rule” can be naturally extended to this bilayer multi-orbital system. Through strong-correlation analysis, two dominant antiferromagnetic superexchange channels are identified: the intralayer same-orbital (d_z²) nearest-neighbor exchange J⊥ mediated by the inner apical oxygen, and the interlayer different-orbital (d_z² and d_x²-y²) nearest-neighbor exchange J_xz mediated by the in-plane oxygen. Due to the bilayer bonding-antibonding splitting and the B₁g symmetry of the d_x²-y² orbital, the two channels cooperate to produce a stable s± superconducting state, characterized by internal sign reversal between the mirror-even and mirror-odd Fermi surface pockets in momentum space. Both pairing channels maximize the superconducting gap on the β pocket with a form factor of (cosk_x − cosk_y)². This result incorporates La₃Ni₂O₇ into the unified framework of unconventional superconductivity while revealing its unique electronic environment for high-temperature superconducting pairing. ...

arXiv Daily: nickelate superconductors 2026-04-19

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. Ultrafast Magneto-Pressure Spectroscopy and Control of Correlated Phases in a Trilayer Nickelate Relevance Score: 5.0119 Authors: Zhi Xiang Chong, Joong-Mok Park, Shuyuan Huyan, Avinash Khatri, Martin Mootz, Xinglong Chen, Daniel P. Phelan, Liang Luo, Ilias E. Perakis, J. F. Mitchell, Sergey L. Bud’ko, Paul C. Canfield, Jigang Wang Affiliations: Ames National Laboratory, Argonne National Laboratory, University of Alabama at Birmingham, Iowa State University Link: http://arxiv.org/abs/2604.16611v1 Summary: This study developed an ultrafast magneto-pressure optical spectroscopy platform capable of operating simultaneously at pressures up to 40 GPa, magnetic fields up to 7 T, and temperatures as low as 5 K, and applied it to investigate the evolution of quasiparticle dynamics under magnetic pressure in the trilayer nickelate Pr₄Ni₃O₁₀. The experiments revealed a pronounced critical slowing down of quasiparticle relaxation near the charge density wave (CDW) transition, which disappears upon the application of pressure. At higher pressures, the low-temperature relaxation time instead becomes longer, consistent with initial superconducting correlation signatures. However, a magnetic field as high as 7 T hardly alters the relaxation behavior, and no vortex-induced pre-bottleneck dynamics—robustly observed in bulk superconducting control samples—was detected, suggesting that any superconducting state under the present pressure conditions is not bulk-like but rather filamentary or strongly inhomogeneous. This magneto-pressure ultrafast capability opens a new pathway for addressing unresolved issues of pressure-induced superconductivity and intertwined orders in correlated quantum materials. ...

arXiv Daily: nickelate superconductors 2026-04-17