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.
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Source: Phys.org