Ultra Low Temperature Scanning Tunneling Microscopy on Turbostratic Graphene

Abstract

Graphene has always been a fascinating material because of its extraordinary properties. These properties can be seen vividly when graphene is suspended. A new multilayer graphene system has been reported as turbostratic graphene, where every layer is decoupled from the other layer. Raman spectra of this system show similar spectra as that of suspended graphene. Graphene produces a pseudo magnetic field in the presence of strain, which re- constructs the band structure into pseudo-Landau levels. However, It is challenging to con- struct a particular strain texture that can produce a pseudo magnetic field over a wide area in an experimental setting. This sample provides a possible pathway to study strain-induced pseudo magnetic fields in suspended graphene in a much more flexible way. In this thesis, I have attempted to investigate properties of turbostratic graphene using Scanning Tunneling Microscopy as well as spectroscopy. A direct measure of the angle between the layers is done using Moire patterns formed as a result of multiple overlaying graphene sheets from scanning tunneling microscopy and a python simulation. We measure the strain-induced pseudo magnetic via the pseudo-Landau levels spectra found by scanning tunneling spec- troscopy. We also try to explore the delocalization of the pseudo magnetic field in the areas near the wrinkle. We have attempted to present turbostratic graphene as a new pathway to strain-induced engineering through this study.