No Strain, No Gain. Modifying 2D Materials by Engineering Strain

Nadya Mason, Dean of the Pritzker School of Molecular Engineering at the University of Chicago, gives a joint Columbia Quantum Initiative Distinguished Speaker Lecture/Columbia Physics C.S. Wu Colloquium on January, 29, 2024.
Abstract | Applying strain can drastically modify the properties of electronic materials-for example, strained silicon transistors showed huge mobility increases that revolutionized the computer industry. Now, there is wide interest in using strain to modify the next generation of electronic materials: two-dimensional systems. 2D materials bridge the limits of superior electric tunability and high mechanical flexibility, making them excellent candidates for mechanical tuning of electronic properties.
Strained graphene, in particular, is predicted to manifest a bandgap opening as well as novel physical effects such as large “pseudo”-magnetic fields. However, it is challenging to create global strain across graphene to modify transport. In this talk, we demonstrate how controllable, global strain in graphene can be engineered by depositing graphene on corrugated substrates.
We show that strained graphene exhibits bandgap openings and pseudomagnetic field effects that depend on the magnitude of induced strain. Control of the strain degree of freedom provides a novel platform both for fundamental studies of 2D electron correlations and for prospective application in 2D electronic devices.