Raman spectroscopy and low temperature magnetotransport studies on hybrid graphene devices

我们打算继续研究混合石墨烯器件的振动和低温磁输运特性，以提高我们对对称态破裂、分数量子霍尔行为和玻色爱因斯坦凝聚等关联现象的理解和扫描。我们将依靠跨导方法，我们已经确定这种方法在揭示有隙或不可压缩的基态方面非常有效。我们将把输运研究扩展到使用电解液门控的高密度区域，以研究能带结构中van Hove奇异性的后果，并验证最近的理论建议，即在足够高的静电掺杂下，可能会在石墨烯中诱导超导电性。这些研究将在石墨烯单层和双层上进行。它们将被放置在BN之上，使用在第一个供资期间开发的精密转移技术，以便为所支持的设备获得尽可能高的质量。对于双层结构，将引入扭转角度作为附加自由度。在基于电解液门控的器件中，我们还将通过循环伏安法来关注在高偏压下可能发生的电化学反应。尽管电化学通常被认为是不可取的，但我们认为这种测量本身很有趣，因为它们揭示了离子通过石墨烯薄片的渗透信息。在多层石墨烯的情况下，这可以认为是电压驱动的插层。我们的主要关注点将是含锂的电解液。

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.