Phys. Rev. Lett. 98, 187204 (2007)

H. Ohldag, T. Tyliszczak, R. Höhne, D. Spemann, P. Esquinazi, M. Ungureanu, and T. Butz

Abstract

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 π-electron system.