The origin of the magnetic anisotropy is explained in an assembly of aligned magnetic nanoparticles. For that, nanoparticles synthesized biologically by Magnetospirillum magneticum AMB-1 magnetotactic bacteria are used. For the first time, it is possible to differentiate between the two contributions arising from the alignment of the magnetosome easy axes and the strength of the magnetosome dipolar interactions. The magnetic anisotropy is shown to arise mainly from the dipolar interactions between the magnetosomes.
Source : Assemblies of aligned magnetotatic bacteria and extracted magnetosomes: What is the main factor responsible for the magnetic anisotropy? E.Alphandry, Y.Ding, A.T.Ngo, Z.LWang, F.F.Wu and M.P.Pileni. ACS Nano, 2009, 3, 1539-1547.