Experimental Quantum Transport Strain Engineering in Graphene

We measure ballistic charge conductivity in strained suspended graphene and observe the theoretically predicted [1] strain-induced scalar and vector potentials. To do so, we built an experimental platform for quantum transport strain engineering in 2D materials. This instrumentation permits low temperature (0.3 K- 70 K) transport, 0T - 9T magnetic fields, and a tunable uniaxial strain (up to 3%) which is independent from the gate-tunable charge density. We show slippage-free clamping of high aspect-ratio graphene crystals where atomically ordered edges are unnecessary for quantitative straintronics. We study in detail transport in a graphene channel whose length is 90 nm and width is 600nm. we observe that both the channel and contacts are ballistic. By applying strain, we find the strain-induced scalar potential which shifts the low energy band structure downward by up to 30 meV. We also clearly observe the effect of a gauge vector potential which reversibly suppresses the conductance by up to 13.6%. We next aim to demonstrate total suppression of conductivity [1] and explore straintronics in other 2D materials.
[1] A. C. McRae, G. Wei, and A. R. Champagne, Phys. Rev. Applied 11, 054019 (2019)