EPSRC DTP PhD studentship: Strain-engineering and pseudo-magnetic fields in graphene nanoresonators

Location: University of Exeter, Streatham Campus, Exeter

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. Raman spectroscopy is a technique whereby one sends in laser light and detects the resultant red-shifted emitted light – the difference in energy is due to, for instance, formation of a phonon. We will engineer the strain in the graphene by applying a voltage to the gate which will distort the graphene membrane suspended above it. Thus we will 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. We will use our Raman measurements to detect the presence of such pseudo-magnetic fields.