Ohldag H, Tyliszczak T, Höhne R, Spemann D, Esquinazi P, Ungureanu M, Butz T
Stanford Synchrotron Radiation Laboratory, Stanford University, P.O. Box 20450, Menlo Park, California 94025, USA.
Phys Rev Lett. 2007 May 4;98(18):187204. doi: 10.1103/PhysRevLett.98.187204. Epub 2007 May 3.
Elemental carbon represents a fundamental building block of matter and the possibility of ferromagnetic order in carbon has attracted widespread attention. However, the origin of magnetic order in such a light element is only poorly understood and has puzzled researchers. We present a spectromicroscopy study at room temperature of proton irradiated metal-free carbon using the elemental and chemical specificity of x-ray magnetic circular dichroism. We demonstrate that the magnetic order in the investigated system originates only from the carbon pi-electron system.
