Spin, Orbital Moment, and Magnetic Order in Fe3O4 Nanoparticle Assemblies

Dr. Karine Chesnel
Department of Physics and Astronomy
Brigham Young University

Magnetite (Fe3O4) particles exhibit a superparamagnetic behavior when their sizes are in nanometer scale. Such nanoparticles could potentially be used for applications in the medical field. We are interested in investigating the magnetic order and fluctuation dynamics in self-assemblies of such nanoparticles. Our Fe3O4 nanoparticles are prepared by an organic route and range from 5 nm to 15 nm in size. They are deposited on membrane where they self-assemble. We have measured the spin and orbital moments in the Fe3O4 nanoparticle assemblies by using X-ray Magnetic Circular Dichroism (XMCD) at the SSRL synchrotron facility in Stanford, and studied how magnetic moments are affected by the particles size and depend on the temperature. In addition, we have studied the magnetic order in the nanoparticle assemblies by using X-ray resonant magnetic scattering (XRMS) This unique technique provides information about the spatial distribution of the particles and their magnetic ordering (1). In addition, the use of coherent light at the SSRL beamline, combined with the application of magnetic field in-situ at different temperatures, allows for studying local magnetic disorder (2) and dynamics of fluctuations near the blocking temperature.

(1) J.B.Kortright et al., PRB 71, 012402 (2005)
(2) K. Chesnel et al., PRB 83, 054436 (2011)

Presentation Slides