Paper

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. [1] High-temperature and high-pressure Raman and infrared spectroscopy reveal that the structural transition from the tilted Amam phase to the untilted Fmmm phase in La₃Ni₂O₇ is accompanied by a metallization transition, but confirm that high symmetry and metallicity alone are insufficient to trigger superconductivity, providing key experimental evidence for the prerequisites of superconductivity. [2] Starting from symmetry and combining DFT+U calculations, it is pointed out that both pressurized bulk and thin films exhibit s±-wave pairing, but the dominant pairing originates from the Ni-dz² out-of-plane orbital and the Ni-dx²-y² in-plane orbital, respectively, and the Tc difference is attributed to the change in the interlayer/intralayer hopping ratio. [3] Using resonant X-ray scattering, it is found in La₂PrNi₂O₇ thin films that superconductivity exists only in regions without spin density wave order and with complete oxygen stoichiometry. It is proposed that oxygen ligand holes are mainly located on the interlayer apical oxygen, forming a stable interlayer five-spin polaron state as the superconducting ground state, emphasizing the key regulatory role of oxygen stoichiometry on interlayer coupling. These results deepen the understanding of the superconducting mechanism in nickelates from three dimensions: structure-electron coupling, pairing symmetry, and oxygen stoichiometry. arXiv submission processing window: 2026-05-05 00:00 to 2026-05-05 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-05

Daily Overview: Today’s highlights focus on advancing the understanding of the electronic structure of hybrid Ruddlesden–Popper nickelates. A study systematically reveals the pressure-driven structural phase transition (from a tilted Amam phase to an untilted phase) in bilayer nickel oxide La₃Ni₂O₇ using high-pressure high-temperature Raman and infrared spectroscopy, along with the accompanying evolution of electronic properties: the transition increases the carrier density by nearly two orders of magnitude, marking a crossover from a bad metal to a good metal, and is closely correlated with the pressure range (approximately 6–7 GPa) where superconductivity emerges. However, high symmetry and metallicity alone are insufficient to induce superconductivity, suggesting that strong electronic correlation effects, such as density wave fluctuations, may play a crucial role, providing important experimental constraints for understanding the mechanism of nickel-based superconductivity. arXiv submission processing window: 2026-05-03 00:25 to 2026-05-03 00:25 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-03

Daily Overview: Based on the list of papers you provided, no research papers directly focusing on nickel-based superconductivity as the core topic were found in today’s overview. Therefore, in accordance with your requirements, a related overall introduction cannot be generated this time. 1. Dimensionality-Driven Electronic and Orbital Transitions Mediating Interfacial Magnetism in LaNiO3/CaMnO3 Observed In Situ Relevance Score: 4.9295 Authors: B-A. Courchene, A. Hampel, S. Beck, J. R. Paudel, J. D. Grassi, L. A. Lapinski, A. M. Derrico, M. Terilli, M. Kareev, C. Klewe, A. Gloskovskii, C. Schlueter, S. K. Chaluvadi, F. Mazzola, I. Vobornik, P. Orgiani, J. Chakhalian, A. J. Millis, A. X. Gray Affiliations: University of California, Berkeley, Lawrence Berkeley National Laboratory, DESY, Temple University, AREA Science Park, Rutgers University, CNR-IOM, Cornell University, Università degli Studi di Padova, Columbia University, Flatiron Institute Link: http://arxiv.org/abs/2604.28054v1 Summary: This study systematically investigates the modulation of interfacial magnetism by dimension-driven electronic and orbital transitions in LaNiO₃/CaMnO₃ superlattices through a combination of in-situ synthesis, polarization-dependent angle-resolved photoelectron spectroscopy, X-ray magnetic circular dichroism, and first-principles electronic structure calculations. It is found that reducing the LaNiO₃ thickness to the ultrathin limit triggers a metal-insulator transition, accompanied by the disappearance of electronic coherence and a crossing of orbital polarization (enhanced in-plane d_x²-y² orbital occupancy). These changes weaken charge transfer at the interface and suppress the interfacial magnetic moment of Mn in CaMnO₃, indicating that the interfacial ferromagnetic state is directly governed by the electronic confinement of LaNiO₃. Density functional theory combined with dynamical mean-field theory successfully reproduces the insulating state and orbital reconstruction. This work confirms a direct and tunable coupling among electronic, orbital, and magnetic degrees of freedom in oxide heterostructures, providing a new pathway for designing correlated electron behavior in nanoscale spintronic materials. ...

arXiv Daily: Nickelate superconductors 2026-05-01

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. Electronic structure, quasiparticle renormalizations, and magnetic correlations in the alternating single-layer bilayer nickelate La$_5$Ni$_3$O$_{11}$ Relevance Score: 5.1402 Authors: I. V. Leonov Link: http://arxiv.org/abs/2604.26627v1 Summary: This study systematically investigates the electronic structure and magnetic correlations in the normal state of the alternating monolayer-bilayer Ruddlesden-Popper nickelate La₅Ni₃O₁₁ (1212-LNO) using the DFT+DMFT method. The results reveal significant differences between structurally distinct monolayer and bilayer Ni ions: the e_g states of bilayer Ni ions form strongly renormalized quasiparticle bands, with effective mass enhancement factors of approximately 3.5 and 4.2 for the Ni x²-y² and 3z²-r² orbitals, respectively; while the e_g states of monolayer Ni ions exhibit an orbital-selective Mott insulating state, where the Ni 3z²-r² orbital possesses a narrow gap and the x²-y² orbital displays metallic but strongly incoherent (non-Fermi liquid) behavior. Magnetic correlation analysis indicates that intertwined spin and charge density wave stripes may form in the bilayer NiO₆ planes, with the primary instability corresponding to an “up-down-0” spin pattern at wave vector Q=(1/3,1/3) competing with a “up-up-down-down” double-stripe state at (1/4,1/4). The 3d electrons of monolayer Ni tend to form Néel-type magnetic order. Under pressure, 1212-LNO undergoes an orbital-selective Mott insulator-metal transition accompanied by the metallization of the monolayer Ni e_g states, which exhibit strongly incoherent non-Fermi liquid behavior near the Fermi level. Overall, correlation effects significantly restructure the magnetic correlations from DFT-predicted monolayer-dominated to bilayer-dominated behavior, emphasizing the critical roles of interlayer confinement and orbital-dependent correlations. ...

arXiv Daily: nickelate superconductors 2026-04-29

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