Adsorption by design: Tuning atom-graphene van der Waals interactions via mechanical strain
Anisotropic Quantum Liquids Spatial dependence of the adsorption potential for a $^4$He adatom ${\sim}3\ \mathrm{\AA}$ above isotropic and anisotropic graphene. Mechanical strain offers an unprecedented experimentally accessible knob to quantum engineer exotic adsorption, interaction, and scattering phenomena near the surface.Abstract
We aim to understand how the van der Waals force between neutral adatoms and a graphene layer is modified by uniaxial strain and electron correlation effects. A detailed analysis is presented for three atoms (He, H, and Na) and graphene strain ranging from weak to moderately strong. We show that the van der Waals potential can be significantly enhanced by strain, and present applications of our results to the problem of elastic scattering of atoms from graphene. In particular, we find that quantum reflection can be significantly suppressed by strain, meaning that dissipative inelastic effects near the surface become of increased importance. Furthermore, we introduce a method to independently estimate the Lennard-Jones parameters used in an effective model of He interacting with graphene, and determine how they depend on strain. At short distances, we find that strain tends to reduce the interaction strength by pushing the location of the adsorption potential minima to higher distances above the deformed graphene sheet. This opens up the exciting possibility of mechanically engineering an adsorption potential, with implications for the formation and observation of anisotropic low-dimensional superfluid phases.
Nathan Nichols
Graduate Student in Materials Science
My research interests include low dimensional exotic phases of matter, quantum Monte Carlo algorithmic development, and machine learning for the quantum many-body problem.