Raman spectroscopy and low temperature magnetotransport studies on hybrid graphene devices

点击翻译按钮获取中文摘要

We intend to continue our investigations of the vibrational and low temperature magneto-transport properties of hybrid graphene devices in order to improve our understanding and scan for correlation phenomena such as broken symmetry states, fractional quantum Hall behaviour and Bose Einstein condensation. We will rely on the transconductance method, which we have identified as very powerful in disclosing gapped or incompressible ground states. We will extend our transport studies to the high density regime using electrolyte gating in order to investigate the consequences of the van Hove singularity in the band structure and verify recent theoretical suggestions that it may be possible to induce superconductivity in graphene at sufficiently high electrostatic doping. These studies will be performed on graphene mono- and bilayers. They will be placed on top of BN using the precision transfer technique developed during the first funding period in order to obtain the highest possible quality for supported devices. For bilayers a twist angle will be introduced as an additional degree of freedom. The twist causes an angle dependent low energy van Hove singularity and therefore represents an important knob to modify the overall electronic bandstructure.In devices based on electrolyte gating, we will also pay attention to electrochemical reactions that may occur at high bias voltages by performing cyclic voltammetry. Even though usually the electrochemistry is considered as undesirable, we consider such measurements interesting all by themselves as they reveal information about the permeation of ions through the graphene sheet. In the case of multilayer graphene, this may be considered as voltage driven intercalation. Our main focus will be on Lithium containing electrolytes.