Magnetic stability of nano-particles: The role of dipolar instability pockets M. Grimsditch, A. Berger, J. Johnson, V. Metlushko, B. Ilic, P. Neuzil and R. Kumar Europhys. Lett., 54 6 (2001) 813-819 Published online: 01 December 2003 DOI: 10.1209/epl/i2001-00326-y