Proton-induced magnetic order in carbon: SQUID measurements

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 256, 412 (2007)
Atomic Collisions in Solids – Proceedings of the 22nd International Conference on Atomic Collisions in Solids, 22nd International Conference on Atomic Collisions in Solids

J. Barzola-Quiquia, P. Esquinazi, M. Rothermel, D. Spemann, A. Setzer and T. Butz


In this work we have studied systematically the changes in the magnetic behavior of highly oriented pyrolytic graphite (HOPG) samples after proton irradiation in the MeV energy range. Superconducting quantum interferometer device (SQUID) results obtained from samples with thousands of localized spots of micrometer size as well on samples irradiated with a broad beam confirm previously reported results. Both, the para- and ferromagnetic contributions depend strongly on the irradiation details. The results indicate that the magnetic moment at saturation of spots of micrometer size is of the order of 10−10 emu.