Their paper describes the fabrication of epitaxial graphene and the first observation of the quantum Hall effect with metrological accuracy.

Until this work, the quantum Hall effect could only be observed in small exfoliated flakes of graphene which are unsuitable for practical applications including metrology.

Many research groups around the world have been striving to obtain this result and it is a real achievement that NPL and its co-workers were the first to observe the effect. The impact is evident from the fact that the paper has already been cited more than 20 times in its first year since publication.

The research is an excellent example of external collaboration between 5 research groups around Europe, combining fabrication, measurement and theory.