Memory effects in superparamagnetic La0.6Pb0.4MnO3 nanoparticles T. Zhang, X. G. Li, X. P. Wang, Q. F. Fang and M. Dressel Eur. Phys. J. B, 74 3 (2010) 309-312 Published online: 18 March 2010 DOI: 10.1140/epjb/e2010-00094-5