期刊
NATURE PHYSICS
卷 8, 期 5, 页码 382-386出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/NPHYS2272
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资金
- US Army Research Laboratory
- US Army Research Office [W911NF-09-1-0333]
- National Science Foundation [DMR-0953784, EECS-0925152, DMR-0706319]
- US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [DE-SC0001819]
- US Office of Naval Research Multi University Research Initiative (MURI) on Graphene Advanced Terahertz Engineering (Gate) at MIT, Harvard
- Boston University
- Swiss Center of Excellence MANEP
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [0953784, 0706319] Funding Source: National Science Foundation
- Div Of Electrical, Commun & Cyber Sys
- Directorate For Engineering [0925152] Funding Source: National Science Foundation
- Grants-in-Aid for Scientific Research [23310096] Funding Source: KAKEN
The Schrodinger equation dictates that the propagation of nearly free electrons through a weak periodic potential results in the opening of bandgaps near points of the reciprocal lattice known as Brillouin zone boundaries(1). However, in the case of massless Dirac fermions, it has been predicted that the chirality of the charge carriers prevents the opening of a bandgap and instead new Dirac points appear in the electronic structure of the material(2,3). Graphene on hexagonal boron nitride exhibits a rotation-dependent moire pattern(4,5). Here, we show experimentally and theoretically that this moire pattern acts as a weak periodic potential and thereby leads to the emergence of a new set of Dirac points at an energy determined by its wavelength. The new massless Dirac fermions generated at these superlattice Dirac points are characterized by a significantly reduced Fermi velocity. Furthermore, the local density of states near these Dirac cones exhibits hexagonal modulation due to the influence of the periodic potential.
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