Structural characterization of electron- and ion-induced defects on HOPG

N,BAJALES; P, FELAJ; S, MONTORO; M, ARANA

Buenos Aires

Workshop; Latin American Workshop on Magnetism, Magnetic Materials and their Applications; 2013

Facultad de Derecho, Universidad de Buenos Aires

ABSTRACTPristine carbon materials are strongly diamagnetic. However, since the early 2000s, the existence of ferro-(antiferro-)magnetic ordering in these materials has become a widely-discussed problem. The topic is still controversial, and experimentalobservations of magnetism have often been attributed to parasitic signals from transition metal impurities [1]. Gradually,magnetism of carbon allotropes is getting more attention, and though the nature of magnetic ordering in all-carbon materials,such as highly oriented pyrolitic graphite (HOPG) is still not completely clear [2], one thing seems evident: for the appearanceof the unconventional magnetism of carbon, irregularities in the carbon lattice are crucial. In particular, ferromagnetismdepending on the irradiation dose has been reported for graphite irradiated with helium and protons [3].In this work we report structural and magnetic characterization of HOPG with defects induced by electron and ion bombardmentfor dierent irradiation doses. In order to characterize small surface changes, we use secondary electron emission(SEE) induced by electron and ion bombardment and Raman spectroscopy. The structural and morphological characterizationis carried out with X-ray diraction, atomic force microscopy and high-resolution scanning electron microscopy. Themagnetic properties are measured with a SQUID and magnetic force microscopy.