Tunable Electronic and Optical Properties in Rotatable and Bendable Van der Waals Heterostructures

MEMS Seminar Series: Professor James Hone, Columbia University

Van der Waals heterostructures, in which different two-dimensional (2D) materials are assembled into layered structures, provide a new opportunity to create tailor-made materials with new properties. Importantly, these properties are a function not only of the constituent materials but also the relative angle between the layers – leading to the new concept of ‘twistronics’. The ultra-low friction between layers in these heterostructures provides a unique opportunity to create tunable materials whose properties can be changed by modifying the interlayer twist angle. To do this, we rotate the top layer of a heterostructure using a contact-mode atomic force microscope (AFM) to modify the interfacial twist angle and moirè wavelength, modifying a number of emergent properties. In this talk I will describe three applications of this technique: (1) tuning bandstructure in graphene-hBN interfaces1; (2) tuning symmetry in graphene with two hBN layers2; and tuning the nonlinear response of hBN-hBN interfaces3. More recently, we have demonstrated tuning by using the AFM to bend thin ‘ribbons’, in which the moiré wavelength and strain vary with position.

Bio: James Hone is currently Wang Fong-Jen Professor of Mechanical Engineering at Columbia University. He received his BS in physics from Yale in 1990, and PhD in experimental condensed matter physics from UC Berkeley in 1998, and did postdoctoral work at the University of Pennsylvania and Caltech, where he was a Millikan Fellow. He joined the Columbia faculty in 2003. He served as director of Columbia’s Materials Research Science and Engineering Center from 2014-2021, and currently serves as chair of the Department of Mechanical Engineering. He is Fellow of the American Physical Society and was awarded the 2023 APS James C. McGroddy Prize for New Materials