Alexandre Champagne1
Concordia University1
We report new measurements of ballistic charge conductivity in strained suspended graphene, and observe the previously predicted [1] strain-induced scalar and vector potentials. To do so, we built an experimental platform for <i>in-situ</i> strain-engineering of quantum transport in 2D materials. This instrumentation permits low temperature (0.3 K) transport in 0 to 9 Tesla magnetic fields. The tunable uniaxial strain (up to 3%) is completely decoupled from the gate-tunable charge density, permitting quantitative understanding of strain effects. We show slippage-free mechanical clamping of high aspect-ratio graphene crystals, where atomically ordered edges are unnecessary for quantitative straintronics. We study in detail transport in a ballistic graphene channel whose length is 90 nm and width is 600 nm. By applying strain in this device, we observe that the strain-induced scalar potential shifts its low energy band structure downward by up to 30 meV. We also show precise control of the gauge vector potential which reversibly suppresses the conductance. We discuss our ongoing experimental progress towards quantum strain engineering in SWCNTs, and present calculations showing their potential for valleytronics and other applications.<br/> <br/>We conclude with an overview of a project to integrate <i>suspended</i> 2D materials in planar optical cavities towards achieving fully tunable nano-opto-electro-mechanical (NOEMS) systems. We developed a nitrocellulose-based (nail polish) method to manipulate very gently and suspend individual ultra-thin 2D materials [2]. Using this method, we assembled optical cavities able to a widely tune Raman scattering and absorption in bilayer graphene. [1] A. C. McRae, G. Wei, and A. R. Champagne, Phys. Rev. Applied 11, 054019 (2019). [2] I. G. Rebollo, F. C. Rodrigues-Machado, W. Wright, G. J. Melin, A. R. Champagne, 2D Mater. 8, 35028 (2021).