Surface effects in nanoparticles: application to maghemite γ-Fe2O3 H. Kachkachi, A. Ezzir, M. Noguès and E. Tronc Eur. Phys. J. B, 14 4 (2000) 681-689 Published online: 15 April 2000 DOI: 10.1007/s100510051079