Patterning Magnetic Graphene With An E-Beam

When it comes to graphene’s properties, the electronic, mechanical, and thermal ones tend to get most of the attention. Researchers devote relatively little effort to exploring its magnetic properties. Yet magnetic forms of graphene, which can be made by hydrogenating the ultrathin carbon material, could be useful for boosting data storage and data transfer technology and for applications in spintronics (spin-based electronics). But those applications would require gentle hydrogenation methods—common ones induce defects in graphene and degrade its properties—and suitable procedures for forming microscopic magnetic patterns. Those applications are now closer at hand as a result of a study led by Woo-Kyung Lee and Paul E. Sheehan of the Naval Research Laboratory, in Washington, D.C. (Adv. Mater. 2015, DOI: 10.1002/adma.201404144). The team hydrogenated graphene by treating it with a solution of ammonia and lithium followed by exposure to ethanol. Then they formed nanoscale patterns by selectively removing hydrogen with an electron beam. Magnetic force microscopy analysis confirms that unlike pristine graphene regions (shown, light background), lightly hydrogenated ones are magnetic (dark squares), and the strength of the magnetism can be tuned by controlling the electron beam intensity.