Using undulations to design novel functionality in 2D materials

Discovering functional quantum materials with desired properties and phenomena is tedious, often involving serendipitous discovery. In my talk, I will cover two examples where introducing undulations in 2D materials can be used as a recipe to induce quantum phases and phenomena. Firstly, I will show that introducing non-Euclidean deformation in 2D materials can create exotic electronic states. By employing elastic plate theory, density-functional, and coarse-grained tight-binding method, I will show that bi-periodic sinusoidal deformation of hBN creates pseudo-electric and magnetic fields with unexpected spatial dependence. [1] A combination of these fields leads to anisotropic confinement and 1D flat bands. The bandwidth of the flat bands can be changed by periodic undulations, which can drive the system to different strongly correlated regimes such as density waves, Luttinger liquid, and Mott insulator. In the second part, I will show how undulations in flat 2D materials break symmetry and create large effective electric fields. The origin of such large electric fields, its connection to flexoelectric voltage, and its implications in designing systems with large Rashba spin-splitting for spintronics-based applications will be presented.

[1] S. Gupta et. al., Nature Communications 13, 3103 (2022)