2D nanocrystal heterostructures - novel production methods and device applications

应变工程是石墨烯研究中的一个新兴领域，它利用了碳原子二维蜂窝状结构的独特物理特性，特别是其对包括机械变形在内的外部影响的适应性。最近一个有趣的预测是，石墨烯晶格的扭曲会产生巨大的伪磁场，这可以通过适当的应变几何来控制。此外，石墨烯带结构的不同谷中的载流子将经历不同的伪磁场，这样的应变可能用于控制未来的石墨烯器件，开辟了“谷电子学”的全新领域，就像电子自旋在自旋电子学或量子计算中的应用一样。该项目将研究应变对悬浮在静电栅极上方的石墨烯拉曼光谱的影响。因此，我们将能够很好地控制和调整这些石墨烯纳米谐振器器件中的应变量，同时研究石墨烯面内和面外变形的拉曼特征。悬浮石墨烯膜的这种不均匀拉伸预计会导致石墨烯表现出均匀的规范场，其作用方式与磁场相似，从而在没有任何外部磁场的情况下产生朗道能级。在这个项目中，我们将开发检测这种伪磁场存在的方法。

Strain-engineering is an emerging field in graphene research that exploits the unique physical properties of this two-dimensional honeycomb structure of carbon atoms, in particular its amenability to external influences, including mechanical deformation. An intriguing recent prediction is that distortion of the graphene lattice creates large pseudo-magnetic fields, which can be controlled with appropriately applied-strain geometry. Furthermore, charge carriers in different valleys of graphene's bandstructure will experience different pseudo-magnetic fields, such that strain might be used to control future graphene devices, opening up the whole new field of 'valleytronics', in a similar fashion to how electron spin is used in spintronics or quantum computing. This project will investigate the effect of strain on the Raman spectra from graphene suspended just above an electrostatic gate. We will thus be able to finely control and tune the amount of strain in these graphene nanoresonator devices, whilst simultaneously studying the Raman signatures of both the in-plane and out-of-plane graphene deformation. Such non-uniform straining of the suspended graphene membrane is expected to result the graphene exhibiting homogeneous gauge fields which act in a similar way to magnetic fields, thereby inducing Landau levels in the absence of any external magnetic fields. During the project we will develop ways to detect the presence of such pseudo-magnetic fields.