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In order to exploit the intriguing optical properties of graphene it is essential to gain a better understanding of the light-matter interaction in the material on ultrashort timescales. Exciting the Dirac fermions with intense ultrafast laser pulses triggers a series of processes involving interactions between electrons, phonons and impurities. Here we study these interactions in epitaxial graphene supported on silicon carbide (semiconducting) and iridium (metallic) substrates using ultrafast time- and angle-resolved photoemission spectroscopy (TR-ARPES) based on high harmonic generation. For the semiconducting substrate we reveal a complex hot carrier dynamics that manifests itself in an elevated electronic temperature and an increase in linewidth of the π band. By analyzing these effects we are able to disentangle electron relaxation channels in graphene. On the metal substrate this hot carrier dynamics is found to be severely perturbed by the presence of the metal, and we find that the electronic system is much harder to heat up than on the semiconductor due to screening of the laser field by the metal.
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http://dx.doi.org/10.1088/0953-8984/27/16/164206 | DOI Listing |
J Am Chem Soc
September 2025
Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Incorporating atomically thin two-dimensional (2D) materials with optical fibers expands their potential for optoelectronic applications. Recent advancements in chemical vapor deposition have enabled the batch production of these hybrid fibers, paving the way for practical implementation. However, their functionality remains constrained by the integration of a single 2D material, restricting their versatile performance.
View Article and Find Full Text PDFSmall
September 2025
Department of Semiconductor Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon, 24341, South Korea.
2D van der Waals ferromagnets hold immense promise for spintronic applications due to their controllability and versatility. Despite their significance, the realization and in-depth characterization of ferromagnetic materials in atomically thin single layers, close to the true 2D limit, has been scarce. Here, a successful synthesis of monolayer (ML) 1T-CrTe is reported on a bilayer graphene (BLG) substrate via molecular beam epitaxy.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Well-defined heterostructures exhibit emergent properties distinct from their single-phase constituents, enabling advances across diverse technologies. Typically classified as self-assembly and epitaxy, heterointerface formation is generally assumed to proceed unidirectionally and irreversibly at bulk scales. Here we use in situ electron microscopy at 298 K to visualize the heterostructure formation from nanoscale mixtures of intrinsically immiscible salts at ambient conditions, NaCl and NaI.
View Article and Find Full Text PDFAdv Sci (Weinh)
September 2025
Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, P. R. China.
Ferrimagnets (FiMs), particularly compensated FiMs, composing of coupled sublattices with antiparallel and inequivalent magnetic moments, present a unique material platform for the regulation of magnetism, which is highly desirable for the design of next-generation spin-based devices. Nevertheless, highly efficient methods for controlling its ferromagnetism remains significantly limited owning to the epitaxial growth required for producing high quality and fully featured films. This study, demonstrates the multiple tunability of ferrimagnetism in the rare-earth iron garnets (REIG: thulium iron garnet) film by incorpoating the graphene interlayers.
View Article and Find Full Text PDFNat Commun
August 2025
The State Key Laboratory of Wide-Bandgap Semiconductor Devices and Integrated Technology, Xi'an, China.
The self-heating effect in wide bandgap semiconductor devices makes epitaxial GaO on diamond substrates crucial for thermal management. However, the lack of wafer-scale single-crystal diamond and severe lattice mismatch limit its industrial application. This study presents van der Waals β-GaO (VdW-β-GaO) grown on high-thermal-conductivity polycrystalline diamond.
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