Origin of Surface Canting within Fe3O4 Nanoparticles

The nature of near-surface spin canting within Fe3O4 nanoparticles is highly debated. Here we develop a neutron scattering asymmetry analysis which quantifies the canting angle to between 23 degrees and 42 degrees at 1.2 T. Simultaneously, an energy-balance model is presented which reproduces the experimentally observed evolution of shell thickness and canting angle between 10 and 300 K. The model is based on the concept of T-d site reorientation and indicates that surface canting involves competition between magnetocrystalline, dipolar, exchange, and Zeeman energies.