Mechanical Control of Quantum Charge and Heat Transport in Ultra-Clean Graphene

Two-dimensional materials are inherently electro-mechanical systems. Graphene’s quantum transport under mechanical strain is still not well understood experimentally. We developed an experimental platform able to fully tune both the mechanics and electrostatics of suspended graphene. Our measurements [1] confirmed that a uniaxial strain can partially suppress graphene’s conductivity, in quantitative agreement with models based on mechanically induced gauge potentials. We could mechanically modify graphene’s work function by up to 25 meV, suppress its ballistic conductance by up to 30 %, and control its quantum interferences. To extend our studies to ultra-clean graphene, while maintaining our ability to apply large variable strains (~ 0 - 2%), we have designed and fabricated a new generation of transistors. Their channels are about 1 micron long, permitting their efficient Joule annealing to reduce their electrostatic disorder (n*~10⁸–10⁹/cm²). We present recent transport measurements in graphene, aiming to (i) completely suppress the charge conductance via mechanical strain and (ii) measure the effect of strain on its electronic thermal conductivity and electron-phonon coupling.

[1] Adv. Mater., 2313629 (2024).