High-energy heavy ion irradiation is a very useful tool for the nanostructuring of 2D materials because defects can be introduced in a controlled way. This approach is especially attractive for the mass production of graphene nanomembranes when nanopore size and density can easily be tuned by ion irradiation parameters such as ion energy and applied fluence. Therefore, understanding the basic mechanisms in nanopore formation due to high-energy heavy ion impact is of the highest importance. In the present work, we used Raman spectroscopy to investigate the response of bilayer and trilayer graphene to this type of irradiation. Spectra obtained from graphene samples irradiated with 1.8 MeV I, 23 MeV I, 3 MeV Cu, 18 MeV Cu, and 12 MeV Si beams were analysed using the Lucchese model. It was found that the efficiency of damage production scales strongly with nuclear energy loss. Therefore, even for the most energetic 23 MeV I beam, the electronic energy loss does not contribute much to damage formation and ion tracks are unlikely to be formed.
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http://dx.doi.org/10.3390/ma16041332 | DOI Listing |
Sci Adv
January 2025
School of Materials Science and Engineering, Peking University, Beijing 100871, P.R. China.
Microcavity exciton polaritons (polaritons) as part-light part-matter quasiparticles garner considerable attention for Bose-Einstein condensation at elevated temperatures. Recently, halide perovskites have emerged as promising room-temperature polaritonic platforms because of their large exciton binding energies and superior optical properties. However, currently, inducing room-temperature nonequilibrium polariton condensation in perovskite microcavities requires optical pulsed excitations with high excitation densities.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Univ Coimbra, Faculdade de Ciências e Tecnologia da Universidade de Coimbra and CFisUC, Rua Larga, 3004-516 Coimbra, Portugal.
The search for primordial black holes (PBHs) with masses M≪M_{⊙} is motivated by natural early-Universe production mechanisms and that PBHs can be dark matter. For M≲10^{14} kg, the PBH density is constrained by null searches for their expected Hawking emission (HE), the characteristics of which are, however, sensitive to new states beyond the standard model. If there exists a large number of spin-0 particles in nature, PBHs can, through HE, develop and maintain non-negligible spins, modifying the visible HE.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Johns Hopkins University, Institute for Quantum Matter and Department of Physics and Astronomy, Baltimore, Maryland 21218, USA.
The tetragonal heavy-fermion superconductor CeRh_{2}As_{2} (T_{c}=0.3 K) exhibits an exceptionally high critical field of 14 T for B∥c. It undergoes a field-driven first-order phase transition between superconducting states, potentially transitioning from spin-singlet to spin-triplet superconductivity.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Xi'an Jiaotong University, School of Microelectronics & State Key Laboratory for Mechanical Behavior of Materials, Xi'an 710049, China.
The bismuth monolayer has recently been experimentally identified as a novel platform for the investigation of two-dimensional single-element ferroelectric system. Here, we model the potential energy surface of a bismuth monolayer by employing a message-passing neural network and achieve an error smaller than 1.2 meV per atom.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Stanford University, Department of Mechanical Engineering, Stanford, California 94305, USA.
The extreme electric fields created in high-intensity laser-plasma interactions could generate energetic ions far more compactly than traditional accelerators. Despite this promise, laser-plasma accelerator experiments have been limited to maximum ion energies of ∼100 MeV/nucleon. The central challenge is the low charge-to-mass ratio of ions, which has precluded one of the most successful approaches used for electrons: laser wakefield acceleration.
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