Journal of Magnetism and Magnetic Materials 322, 1228 (2010)

M. Dubman, T. Shiroka, H. Luetkens, M. Rothermel, F.J. Litterst, E. Morenzoni, A. Suter, D. Spemann, P. Esquinazi, A. Setzer and T. Butz

Abstract

Low-energy muon spin rotation and SQUID magnetization measurements were performed on proton-irradiated and non-irradiated highly oriented pyrolytic graphite samples. The samples were found to be ferromagnetic above and below room temperature and to include a substantial temperature-dependent surface contribution. Assuming uniformity, the thickness of the magnetic surface layer was estimated to be 13(2) nm. The discovered surface magnetism is intrinsic and not due to irradiation.

Keywords: Magnetic carbon; Surface magnetism; Irradiation effect; Low-energy μSR

PACS classification codes: 75.50.Pp; 78.70.−g; 76.75.+i