Graphene Materials & Devices
Graphene is a single sheet of carbon atoms with the honeycomb structure of graphite as illustrated n Figure 1. It was the first truly two dimensional solid material shown to exist in a stable form. Our group has been working on this material since it was first isolated here in the Manchester Centre for Mesoscience and Nanotechnology in 2004 . We use the peel cleaving of Graphite (or “Scotch Tape Technique”) to generate flakes of single layer graphene as shown in Figure 2.
Figure 1: Graphene
Figure 2: One atomic plane deposited on SiO2
The flake quality is very high and is the starting material for a range of device studies which include:
i) Graphene Based Sensors
This work has shown that single gas molecule detection is possible using adsorbtion and desorbtion onto a graphene conductor. Figure 3 shows it is possible to see changes in the Hall resistance equivalent to one electronic charge being accepted or donated as the gas molecule is adsorbed or desorbed from the surface (see Ref. ).
Figure 3: Step-like changes in Hall conductivity near zero concentration
We are also using graphene as a high mobility material for making very high sensitivity Hall Effect devices with active areas of a 100 nm by 100nm and below. These small devices can be used to probe the magnetism of magnetic nano-dots which have potential applications in magnetic data storage.
ii) Graphene spin valves
We were the first group to demonstrate a spin valve effect in graphene  and we are currently working on spin transport through graphene and other two dimensional materials. Graphene is potentially an important material for spintronic devices due to its large spin diffusion length and ballistic charge transport properties.
iii) Magnetism in Graphene
We have an interest in the magnetic properties of graphene through a project lead by the Condensed Matter Physics Group. The aim is to study the magnetic properties of graphene using conventional magnetometry methods and to investigate the interaction effects from uncompensated spins at edges which could possibly give rise to a ferromagnetic state.
- Novoselov, K.S., et al., Electric field effect in atomically thin carbon films. Science, 2004. 306(5696): p. 666-669.
- Novoselov, K. and A. Geim, Graphene detects single molecule of toxic gas. Materials Technology, 2007. 22: p. 178-179.
- Hill, E.W., et al., Graphene spin valve devices. Ieee Transactions on Magnetics, 2006. 42(10): p. 2694-2696.