Today at Berkeley Lab

Advanced Light Source Reveals Mysteries of Magnetic Carbon

Can you really make a magnet out of pencil lead? It doesn’t seem likely. Yet when a kind of graphite made by cooling hot carbon is exposed to a magnetic field, it produces an opposing field. Although this “highly oriented pyrolytic graphite” (HOPG) isn’t magnetic without help from an external field, the effect encourages theorists who propose making carbon magnets by doping carbon with hydrogen. “Experimental proof has been elusive until now,” says Hendrik Ohldag of the Stanford Synchrotron Radiation Lightsource. He and his colleagues, including Elke Arenholz of the Advanced Light Source, used ALS beamline 4.0.2 to study HOPG irradiated with protons (hydrogen nuclei). “We found that the hydrogen atoms incorporated at the surface switched on a very large magnetic moment in our graphite samples—comparable to that of iron, nickel, or cobalt—even at room temperature.” The next step is to reproduce the effect in single-atomic-layer graphene. Says Ohldag: “Graphene’s applications seem to be endless, and now we may have added another one.” More>