[OPEN ACCESS] Quantitative spatial magnetization distribution in iron oxide nanocubes and nanospheres by polarized small-angle neutron scattering

http://stacks.iop.org/1367-2630/14/013025 [OPEN ACCESS]

New Journal of Physics, 2012, 14, 013025

Sabrina Disch, Erik Wetterskog, Raphaël P. Hermann, Albrecht Wiedenmann, Ulla Vainio, German Salazar-Alvarez, Lennart Bergström and Thomas Brückel

DOI: 10.1088/1367-2630/14/1/013025

By means of polarized small-angle neutron scattering, we have resolved the long-standing challenge of determining the magnetization distribution in magnetic nanoparticles in absolute units. The reduced magnetization, localized in non-interacting nanoparticles, indicates strongly particle shape- dependent surface spin canting with a 0.3(1) and 0.5(1) nm thick surface shell of reduced magnetization found for ~9 nm nanospheres and ~8.5 nm nanocubes, respectively. Further, the reduced macroscopic magnetization in nanoparticles results not only from surface spin canting, but also from drastically reduced magnetization inside the uniformly magnetized core as compared to the bulk material. Our microscopic results explain the low macroscopic magnetization commonly found in nanoparticles.