Graphene is a two-dimensional honeycomb lattice of carbon atoms which was first systematically isolated by mechanical exfoliation from bulk graphite in 2004 , and is a material that presents many interesting properties . For example, the envelope function equation of graphene formally coincides with the relativistic wave equation of massless spin-1/2 particles (the Dirac–Weyl equation) . This has made it possible to experimentally observe relativistic phenomena such as Klein tunneling, Zitterbewegung, and anomalous quantum Hall effect, at the low energies that are typical of condensed matter physics . Moreover, graphene is a one-atom-thick material that is light and flexible but with a large mechanical strength, it has very high electrical and thermal mobilities, and is transparent and impermeable. Many applications have been proposed for it, some of which are rapidly finding their way to the market .