Spin structures in antiferromagnetic nanoparticles

Erik Brok (Department of Physics, Technical University of Denmark)

In nanoparticles the spin structure can be different from that of the corresponding bulk system due to the following reasons: a) a significant surface contribution to the magnetic anisotropy, b) the low symmetry environment of surface atoms leading to non collinear spin structures, and c) exchange interactions between neighboring particles. The spin structure is important for the magnetic properties of materials and is therefore relevant both from the point of view of basic science and applications. Because of the absence of a dominating dipole field antiferromagnetic nanoparticles are ideal for studying the finite size effects on spin structures, and in particular for studying exchange interactions.

In this seminar results on the spin structure, in particular the orientation of the spins in the antiferromagnetic sublattices, are presented for plate shaped NiO nanoparticles, natural $\alpha$-Fe2O3-FeTiO3 nanoscale intergrowths, and ultrafine $\alpha$-FeOOH nanoparticles. These systems are investigated with a range of experimental techniques. Here particular attention will be given to results from experiments utilizing the advantages of polarized neutron scattering to obtain information about spin orientation and to separate magnetic, nuclear and spin incoherent scattering.

Back to Seminar Home Page

Last modified 14-February-2014 by website owner: NCNR (attn: )