Speaker
Eugene Mele
(University of Pennsylvania)
Description
Twisted graphenes are a family of multilayer graphenes in
which the crystallographic axes of neighboring layers are
rotated by angles \theta \neq n \pi/3. Experimentally the
misalignment is associated with a reduction of the energy
scale for coherent interlayer electronic motion relative to its
known value for Bernal stacked graphenes and for related
multilayer graphenes where \theta \eq n \pi/3. The
microscopic origin and nature of this reduction is attracting
significant theoretical interest. In this work we focus on the
physics for small rotation angles, a regime where a
continuum treatment is thought to be valid, and find that
rotational anisotropy in the interlayer coupling Hamiltonian
plays an unexpected role by selecting one of two
geometrically distinct electronic states for the coupled
system. This talk will discuss the topological classification of
these states and their spectral signatures.
