Symmetry analysis shows orbital hybridization vanishes along the BZ diagonal, allowing the gap on alpha/beta pockets to test d_x2-y2 vs d_z2 dominance; experiments and RPA favor Hund's rule mechanism with full gap.
Atomically resolved intrinsic superconducting gap in (La,Pr)3Ni2O7 films
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abstract
Ruddlesden-Popper bilayer nickelates provide an emerging platform for studying high-temperature superconductivity, yet the superconducting pairing symmetry remains under debate. Here, we use atomic-resolution scanning tunnelling microscopy and spectroscopy to investigate superconducting 1.5-unit-cell (La,Pr)3Ni2O7 films grown on SrLaAlO4. A cryogenic ultrahigh-vacuum (UHV) sample transfer preserves an ordered sqrt(2) * sqrt(2) surface and yields reproducible U-shaped spectra with two gap scales of ~14 and ~20 meV and extended flat zero-conductance bottoms. By contrast, samples exposed for a longer time in UHV without cooling during transfer show V-shaped spectra despite retaining the surface reconstruction and a transport superconducting transition onset above 40 K. Wide-energy-range spectra indicate that oxygen loss can mix density-wave-related spectral weight. Our measurements provide an atomic-scale observation of the intrinsic nodeless superconducting gap in bilayer nickelate ultrathin films.
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cond-mat.str-el 1years
2026 1verdicts
UNVERDICTED 1representative citing papers
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What Does the Single-Particle Spectrum Imply on the Pairing Nature and Pairing Mechanism in La$_3$Ni$_2$O$_7$?
Symmetry analysis shows orbital hybridization vanishes along the BZ diagonal, allowing the gap on alpha/beta pockets to test d_x2-y2 vs d_z2 dominance; experiments and RPA favor Hund's rule mechanism with full gap.