103 research outputs found
Evolution of plasmon excitations across the phase diagram of the cuprate superconductor LaSrCuO
We use resonant inelastic x-ray scattering (RIXS) at the O - and Cu
-edges to investigate the doping- and temperature dependence of low-energy
plasmon excitations in LaSrCuO. We observe a monotonic
increase of the energy scale of the plasmons with increasing doping in the
underdoped regime, whereas a saturation occurs above optimal doping and persists at least up to . Furthermore, we find that the
plasmon excitations show only a marginal temperature dependence, and possible
effects due to the superconducting transition and the onset of strange metal
behavior are either absent or below the detection limit of our experiment.
Taking into account the strongly correlated character of the cuprates, we show
that layered -- model calculations accurately capture the increase of
the plasmon energy in the underdoped regime. However, the computed plasmon
energy continues to increase even for doping levels above ,
which is distinct from the experimentally observed saturation, and reaches a
broad maximum around . We discuss whether possible lattice disorder
in overdoped samples, a renormalization of the electronic correlation strength
at high dopings, or an increasing relevance of non-planar Cu and O orbitals
could be responsible for the discrepancy between experiment and theory for
doping levels above .Comment: 19 pages, 11 figure
Gapped collective charge excitations and interlayer hopping in cuprate superconductors
We use resonant inelastic x-ray scattering (RIXS) to probe the propagation of
plasmons in the electron-doped cuprate superconductor
SrLaCuO (SLCO). We detect a plasmon gap of ~120 meV
at the two-dimensional Brillouin zone center, indicating that low-energy
plasmons in SLCO are not strictly acoustic. The plasmon dispersion, including
the gap, is accurately captured by layered -- model calculations. A
similar analysis performed on recent RIXS data from other cuprates suggests
that the plasmon gap is generic and its size is related to the magnitude of the
interlayer hopping . Our work signifies the three-dimensionality of the
charge dynamics in layered cuprates and provides a new method to determine
.Comment: 17 pages, 10 figures, includes Supplemental Material. Accepted for
publication in Physical Review Letter
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Electronic structure of the parent compound of superconducting infinite-layer nickelates.
The search continues for nickel oxide-based materials with electronic properties similar to cuprate high-temperature superconductors1-10. The recent discovery of superconductivity in the doped infinite-layer nickelate NdNiO2 (refs. 11,12) has strengthened these efforts. Here, we use X-ray spectroscopy and density functional theory to show that the electronic structure of LaNiO2 and NdNiO2, while similar to the cuprates, includes significant distinctions. Unlike cuprates, the rare-earth spacer layer in the infinite-layer nickelate supports a weakly interacting three-dimensional 5d metallic state, which hybridizes with a quasi-two-dimensional, strongly correlated state with [Formula: see text] symmetry in the NiO2 layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare-earth intermetallics13-15, which are well known for heavy fermion behaviour, where the NiO2 correlated layers play an analogous role to the 4f states in rare-earth heavy fermion compounds. This Kondo- or Anderson-lattice-like 'oxide-intermetallic' replaces the Mott insulator as the reference state from which superconductivity emerges upon doping
Spectroscopic fingerprint of charge order melting driven by quantum fluctuations in a cuprate
Theoretical Physic
Electronic structure of the parent compound of superconducting infinite-layer nickelates
Theoretical Physic
Rescue of American chestnut with extraspecific genes following its destruction by a naturalized pathogen
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