Magnetic stability of nano-particles: The role of dipolar instability pocketsM. Grimsditch, A. Berger, J. Johnson, V. Metlushko, B. Ilic, P. Neuzil and R. KumarEurophys. Lett., 54 6 (2001) 813-819DOI: https://doi.org/10.1209/epl/i2001-00326-y