Strain-Engineering the Gauge Potential of Dirac fermions in PECVD-grown Graphene

Non-trivial strain can induce pseudo-magnetic fields in graphene so that the electronic properties of Dirac fermions can be tuned by controlling the strain on graphene. Here we employ nearly strain-free single-domain PECVD-graphene$^{\mathrm{1}}$ to induce controlled strain by placing graphene on nanostructured substrates. Strain-induced gauge potentials and pseudo-magnetic fields can be manifested by the local tunneling conductance peaks at quantized energies.$^{\mathrm{2,3}}$ Additionally, pseudo-magnetic field-induced local spontaneous time-reversal symmetry breaking can be revealed by spatially alternating presence and absence of the zero mode in the tunneling conductance spectra.$^{\mathrm{2,3}}$ We also employ molecular dynamics simulations to determine the spatial distribution of the pseudo-magnetic field for a given nanostructure. We find that a tetrahedron-like nanostructure can be an effective “valley splitter” to separate the trajectories of Dirac fermions of opposite pseudo-spins. Proper design and arrangement of several valley filters can function as a “valley propagator” to guide valley-polarized currents. We plan to verify the valley Hall effect associated with a valley splitter and to assess the feasibility of realistic valleytronic applications. 1. D.A. Boyd et al. Nat. Comm. 6, 6620 (2015). 2. N.-C. Yeh et al. Surface Science 605, 1649-1656 (2011). 3. N.-C. Yeh et al. Acta Mechanica Sinica (in press).