Edge states are an emerging concept in physics and
have been explored as an efficient strategy to manipulate
electrons, photons and phonons for next-generation hybrid
electro-optomechanical circuits. Scientists have used gapless
chiral edge states in graphene or graphene-like materials to
understand exotic quantum phenomena such as quantum spin or valley
Hall effects. In a new report now published on Science Advances,
Xiang Xi and colleagues reported on experimental chiral edge states
in gapped nanomechanical graphene; a honeycomb lattice of
free-standing silicon nitride nanomechanical membranes with broken
spatial inversion symmetry (presence of a dipole). The constructs
were immune against backscattering in sharp bends and exhibited the
valley-momentum locking effect. The team realized a smooth
transition between the chiral edge states and the well-known valley
kink states to open the door for experimental investigations of
soft graphene-related physics in very-high-frequency, integrated
nanomechanical systems.
