Abstract Details

How to Turn Carbon into a Ferromagnet? – X-rays and Protons can Give the Answer?
Abstract ID	LCLS/SSRL-20
Presenter	Hendrik  Ohldag
Presentation Type	LCLS/SSRL Invited Speaker
Full Author List	H. Ohldag (1) , T. Tyliszczak (2) , R. Hohne (3) , D.Spemann (3) , P. Esquinazi (3) , M. Ungureneau (3) , T. Butz (3)
Affiliations	(1) Stanford Synchrotron Radiation Laboratory (2) Advanced Light Source (3) University of Leipzig
Category	Materials Science
Abstract	While conventional wisdom says that magnetic materials have to contain some metallic atoms, the confirmation of intrinsic magnetic order in pure metal free carbon represents an ultimate and general scientific breakthrough because of the fundamental importance of carbon as an elemental building block of organic as well as inorganic matter. The common controversy raised across all disciplines is whether the magnetism of carbon is intrinsic or induced by other elements. We address this controversy by providing clear experimental evidence that metal free carbon can be ferromagnetic at room temperature using dichroism x-ray absorption spectro-microscopy. For this purpose we acquired soft x-ray microscopy images of magnetic structures on a thin carbon film that have been produced by irradiation with a focused 2.25MeV proton beam [1]. Our element specific magnetic probe shows no indication of magnetically ordered Fe, Co or Ni impurities in these samples. The x-ray microscopy images provide a convincing experimental picture that the macroscopically observed magnetic order is indeed caused exclusively by the carbon atoms [2] since only the carbon Pi electronic states show x-ray magnetic circular dichroism.
Footnotes	References [1] P. Esquinazi et al., PRL 91, p 227201 (2003) [2] H. Ohldag et al., PRL 98, p. 187204 (2007)
Funding Acknowledgement