 Award ID(s):
 1853048
 Publication Date:
 NSFPAR ID:
 10326669
 Journal Name:
 SciPost Physics
 Volume:
 12
 Issue:
 4
 ISSN:
 25424653
 Sponsoring Org:
 National Science Foundation
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Abstract The proposal that core collapse supernovae are neutrino driven is still the subject of active investigation more than 50 years after the seminal paper by Colgate and White. The modern version of this paradigm, which we owe to Wilson, proposes that the supernova shock wave is powered by neutrino heating, mediated by the absorption of electronflavor neutrinos and antineutrinos emanating from the protoneutron star surface, or neutrinosphere. Neutrino weak interactions with the stellar core fluid, the theory of which is still evolving, are flavor and energy dependent. The associated neutrino mean free paths extend over many orders of magnitude and are never always small relative to the stellar core radius. Thus, neutrinos are never always fluid like. Instead, a kinetic description of them in terms of distribution functions that determine the number density of neutrinos in the sixdimensional phase space of position, direction, and energy, for both neutrinos and antineutrinos of each flavor, or in terms of angular moments of these neutrino distributions that instead provide neutrino number densities in the fourdimensional phasespace subspace of position and energy, is needed. In turn, the computational challenge is twofold: (i) to map the kinetic equations governing the evolution of these distributionsmore »

Tuning interactions between Dirac states in graphene has attracted enormous interest because it can modify the electronic spectrum of the twodimensional material, enhance electron correlations, and give rise to novel condensedmatter phases such as superconductors, Mott insulators, Wigner crystals and quantum anomalous Hall insulators. Previous works predominantly focus on the flat band dispersion of coupled Dirac states from different twisted graphene layers. In this work, we propose a new route to realizing flat band physics in monolayer graphene under a periodic modulation from substrates. We take graphene/SiC heterostructure as a prototypical example and demonstrate experimentally that the substrate modulation leads to Dirac fermion cloning and consequently, the proximity of the two Dirac cones of monolayer graphene in momentum space. Our theoretical modeling captures the cloning mechanism of Dirac states and indicates that Moiré flat bands can emerge at certain magic lattice constants of the substrate, specifically when the period of modulation becomes nearly commensurate with the (√3×√3)𝑅30∘ supercell of graphene. The results show that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic manybody quantum phases arising from interactions between Dirac electrons.

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