High temperature superconductivity in cuprates arises from doping a parent Mott insulator by electrons or holes. A central issue is how the Mott gap evolves and the low-energy states emerge with doping. Here we report angle-resolved photoemission spectroscopy measurements on a cuprate parent compound by sequential in situ electron doping. The chemical potential jumps to the bottom of the upper Hubbard band upon a slight electron doping, making it possible to directly visualize the charge transfer band and the full Mott gap region. With increasing doping, the Mott gap rapidly collapses due to the spectral weight transfer from the charge transfer band to the gapped region and the induced low-energy states emerge in a wide energy range inside the Mott gap. These results provide key information on the electronic evolution in doping a Mott insulator and establish a basis for developing microscopic theories for cuprate superconductivity.
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http://dx.doi.org/10.1038/s41467-021-21605-6 | DOI Listing |
ACS Nano
January 2025
School of Information Science and Technology and Department of Optical Science and Engineering and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai 200433, China.
The formation of large polarons resulting from the Fröhlich coupling of photogenerated carriers with the polarized crystal lattice is considered crucial in shaping the outstanding optoelectronic properties in hybrid organic-inorganic perovskite crystals. Until now, the initial polaron dynamics after photoexcitation have remained elusive in the hybrid perovskite system. Here, based on the terahertz time-domain spectroscopy and optical-pump terahertz probe, we access the nature of interplay between photoexcited unbound charge carriers and optical phonons in MAPbBr within the initial 5 ps after excitation and have demonstrated the simultaneous existence of both electron- and hole-polarons, together with the photogenerated carrier dynamic process.
View Article and Find Full Text PDFImplement Res Pract
January 2025
School of Global Public Health, New York University, New York, NY, USA.
Background: Community access to evidence-based information is critical, especially during a pandemic, as it can impact knowledge and adoption of health behaviors that affect health disparities. The field of dissemination and implementation (D&I) science is ideally positioned to address this need through its focus on reducing the research-to-practice gap through improved distribution of information. The purpose of this paper is to describe the creation of a weekly webinar series about COVID-19 directed toward community members, and the extent to which webinars were found useful and increased awareness of evidence-based information and services.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
The pseudogap phenomena have been a long-standing mystery of the cuprate high-temperature superconductors. The pseudogap in the electron-doped cuprates has been attributed to band folding due to antiferromagnetic (AFM) long-range order or short-range correlation. We performed an angle-resolved photoemission spectroscopy study of the electron-doped cuprates PrLaCeCuO showing spin-glass, disordered AFM behaviors, and superconductivity at low temperatures and, by measurements with fine momentum cuts, found that the gap opens on the unfolded Fermi surface rather than the AFM Brillouin zone boundary.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C 8000, Denmark.
Superlattices from twisted graphene mono- and bilayer systems give rise to on-demand many-body states such as Mott insulators and unconventional superconductors. These phenomena are ascribed to a combination of flat bands and strong Coulomb interactions. However, a comprehensive understanding is lacking because the low-energy band structure strongly changes when an electric field is applied to vary the electron filling.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China.
Photocatalytic technology holds significant promise for sustainable development and environmental protection due to its ability to utilize renewable energy sources and degrade pollutants efficiently. In this study, BiOI nanosheets (NSs) were synthesized using a simple water bath method with varying amounts of mannitol and reaction temperatures to investigate their structural, morphological, photoelectronic, and photocatalytic properties. Notably, the introduction of mannitol played a critical role in inducing a transition in BiOI from an n-type to a p-type semiconductor, as evidenced by Mott-Schottky (M-S) and band structure analyses.
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