Paper

Daily Overview: Today’s highlight work focuses on the exploration of a peculiar superconducting phase-transition phenomenon in infinite-layer nickelates. A study has realized an “inverse superconducting transition” that exceeds the liquid‑helium cooling limit in Eu‑based infinite‑layer nickelates (EuₓNd₁₋ₓNiO₂ and EuₓPr₁₋ₓNiO₂). It is found that, through magnetic‑field tuning, the superconducting zero‑resistance state is confined to a specific window between a lower turnover temperature and a higher normal superconducting critical temperature, manifested by the fact that raising the temperature or increasing the current density can paradoxically drive the system from a resistive state into a superconducting state. This anomalous behavior is attributed to the temperature‑induced alternation in the relative strength of the Eu²⁺ 4f⁷‑related compensating effective field and the upper critical field, and is corroborated by the re‑emergence of superconductivity at very low temperatures. The discovery not only offers a new paradigm for constructing high‑temperature superconducting systems with tunable magnetic interactions, but also opens up fresh application prospects for exploring quantum phenomena that reverse thermal decoherence and for the inverse design of quantum‑phase‑transition devices. arXiv submission processing window: 2026-06-18 00:00 to 2026-06-18 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-18

Daily Overview: Today’s highlights center on an in-depth understanding of the electronic structure of hybrid Ruddlesden–Popper nickelates. A theoretical study on 1313-La₃Ni₂O₇ thin films reveals the critical role of strain in tuning superconductivity: compressive strain suppresses superconductivity, whereas tensile strain induces band reconstruction in the trilayer subsystem, generating a new hole-like γ pocket that can drive an s±-wave pairing state with a sign-reversed order parameter, thereby establishing design principles for achieving superconductivity at ambient pressure through strain engineering. Complementarily, another work addresses the long-standing challenge of severe spectral overlap between La 3d and Ni 2p signals in nickelate spectroscopy. By innovatively employing Ni 1s core-level hard X-ray photoelectron spectroscopy, the study successfully extracts interference-free information on charge-transfer excitations in La-based nickelates, uncovering differences in nickel–ligand hybridization strength between La₃Ni₂O₇ and Nd₃Ni₂O₇ induced by tensile strain. This advance provides a sensitive and reliable spectroscopic method for systematically disentangling the effects of strain, doping, and other factors on the electronic structure of nickelates. arXiv submission processing window: 2026-06-17 00:00 to 2026-06-17 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-17

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of hybrid Ruddlesden–Popper nickelates. In [1], first-principles calculations reveal the coupling between chemical-pressure-driven structural phase transitions and the emergence of superconductivity in rare-earth-doped La₂RNi₂O₇ (R=Pr, Nd, Sm), along with the key characteristic that the d_(z²) orbital forms a hole-type Fermi surface at the Fermi level in the high-pressure tetragonal phase, and elucidate the importance of out-of-plane – in-plane orbital hybridization for superconducting pairing. In resonance, [2] systematically reviews the interlayer pairing picture of bilayer nickelates from a strong-correlation perspective, emphasizing the phase coherence provided by the hybridization of localized d_(z²) pairs with itinerant d_(x² − y²). Building on this, [3] employs a t − J model incorporating d_(z²) and d_(x² − y²) orbitals to deliver a unified superconducting theory covering both bulk and thin films, predicts distinct superconducting domes under electron/hole doping, and points out that weakening interlayer coupling could realize superconductivity at ambient pressure. Regarding the origin of magnetism, [4] proposes an itinerant spin-density-wave picture, in which mirror-selective interband nesting not only explains the small net magnetic moments and spin-wave-like excitations in La₃Ni₂O₇ and La₄Ni₃O₁₀, but also clarifies the intertwining of spin and charge orders. Furthermore, [5] uses resonant inelastic X‑ray scattering to observe plasmons for the first time in metallic Pr₄Ni₃O₈; comparison with cuprates reveals weaker electronic transitions and enhanced screening effects in the nickelates, providing direct experimental evidence to quantitatively define the key energy scales of superconductivity. arXiv submission processing window: 2026-06-16 00:00 to 2026-06-16 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-16

Daily Overview: Today’s highlight focuses on revealing the intrinsic electronic structure and pairing mechanism of nickelate superconductors from multiple dimensions. In superconducting bilayer nickel oxide thin films, study [1] employs resonant X-ray scattering and spectroscopy to clarify the spatial separation between superconductivity and spin density wave order, and proposes a novel interlayer five-spin polaron state in which the Ni(d⁸)-O(L)-Ni(d⁸) configuration locks out-of-plane orbital charge and spin, leaving the in-plane orbitals near half-filling, thereby elucidating the critical role of oxygen stoichiometry in tuning interlayer coupling and the electronic ground state. For the trilayer nickel oxide La₄Ni₃O₁₀, theoretical calculations in study [2] demonstrate that pressure can induce additional hole transfer from apical to planar oxygens, forming freely propagating in-plane three-spin polaron quasiparticles, thus providing a natural microscopic mechanism for the emergence of superconductivity in the high-pressure phase. Furthermore, study [3] uses ultrafast terahertz spectroscopy in infinite-layer samarium nickel oxide thin films to observe a linear temperature response of the superfluid density, extract a clean d-wave pairing gap, and confirm that the system resides in the weak-coupling clean limit, directly demonstrating a profound similarity in pairing symmetry between nickel-based superconductors and cuprate high-temperature superconductors. arXiv submission processing window: 2026-06-12 00:00 to 2026-06-12 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-12

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of hybrid Ruddlesden–Popper nickelates. Two resonant inelastic X‑ray scattering studies reveal, from the perspectives of doping and strain respectively, the intrinsic connection between spin excitations and superconductivity in bilayer nickelates: in La₃₋ₓSrₓNi₂O₇ thin films, beyond the superconducting dome, coherent spin excitations undergo magnetic collapse, with their quenching occurring concurrently with the reconstruction of the apical‑oxygen‑mediated d_(z²)–p_z–d_(z²) orbitals, clearly indicating that maintaining a local d_(z²) magnetic structure and robust interlayer apical‑oxygen coupling is a fundamental prerequisite for achieving high‑temperature superconductivity. Meanwhile, strain engineering of La₃Ni₂O₇ thin films demonstrates that compressive strain enhances the interlayer antiferromagnetic superexchange J_z accompanied by the emergence of superconductivity, while tensile strain markedly suppresses spin excitations and d_(z²)‑related excitations, providing direct spectroscopic evidence for the theoretical picture of pairing promoted by interlayer antiferromagnetic superexchange. In addition, a first‑principles calculation reveals a unique bipartite electronic system in a new bilayer nickel oxide, La₃Ni₂O₅F, where conventional Ni dpσ hole carriers coexist with E* electron carriers originating from interstitial electronic states, forming a cylindrical electron Fermi surface and velocity‑parallel potential Dirac points. This two‑component electronic configuration is expected to induce unconventional superconducting behavior, offering a possible route toward new designs of apical‑oxygen‑free nickelate superconductors. arXiv submission processing window: 2026-06-10 00:00 to 2026-06-10 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-10