PerspectivePhysics

Painting magnetism on a canvas of graphene

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Science  22 Apr 2016:
Vol. 352, Issue 6284, pp. 415-416
DOI: 10.1126/science.aaf4521

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Summary

An inherent aspect of any two-dimensional (2D) sheet is that all atoms in the material lie on the surface. This leads to a concept of 2D crystals as a “canvas,” where different chemical groups or “ink” on the surface can lead to a palette of distinct materials properties. The most well-studied 2D crystal is graphene, a one-atom-thick sheet of carbon atoms arranged in a honeycomb lattice. Although graphene's superlative materials properties and novel physical phenomena have led to a variety of applications (1), better tunability of these properties is still required. Toward this end, hydrogenated graphene (graphane) was predicted to have a wide band gap and exhibit magnetic order (24), in contrast to graphene, which is (semi)metallic and diamagnetic. The chemical stability of graphene makes hydrogenation difficult to control, and this has hampered efforts to tune its electronic or magnetic properties. On page 437 of this issue, González-Herrero et al. (5) report direct evidence that hydrogen atoms on graphene do indeed yield a magnetic moment and that these moments can order ferromagnetically over relatively large distances. If these methods can be extended to industrial scales, then one can imagine storing information at unprecedented densities by painting magnetic bits on graphene canvases (see the figure).