Geology

Bilayer graphene

Electron

Graphene

Optics

Femtosecond

Bilayer

Quantum mechanics

Oceanography

Condensed matter physics

Ultrashort pulse

Biochemistry

Nanotechnology

Membrane

Chemical physics

Substrate (aquarium)

Chemistry

Materials science

Physics

Laser

ACS Nano

Ultrafast carrier dynamics in a graphene system are very important in terms of optoelectronic devices. Recently, a twisted bilayer graphene has been discovered that possesses interesting electronic properties owing to strong modifications in interlayer couplings. Thus, a better understanding of ultrafast carrier dynamics in a twisted bilayer graphene is highly desired. Here, we reveal the unbalanced electron distributions in a quasicrystalline 30° twisted bilayer graphene (QCTBG), using time- and angle-resolved photoemission spectroscopy on the femtosecond time scale. We distinguish time-dependent electronic behavior between the upper- and lower-layer Dirac cones and gain insight into the dynamical properties of replica bands, which show characteristic signatures due to Umklapp scatterings. The experimental results are reproduced by solving a set of rate equations among the graphene layers and substrate. We find that the substrate buffer layer plays a key role in initial carrier injections to the upper and lo...

Ultrafast Unbalanced Electron Distributions in Quasicrystalline 30° Twisted Bilayer Graphene