Magnetic properties of barium ferrite nanoparticles: Quantitative test of the Stoner–Wohlfarth theory for uniaxial single-domain magnetic particles.

Abstract: We have successfully synthesized single-domain barium ferrite particles with uniaxial anisotropy. We have coated them with amorphous silica to reduce interparticle interactions so that the assembly of these particles behaves like a noninteracting randomly oriented uniaxial single-domain particle system, a prototype for the Stoner–Wohlfarth model. From the magnetic hysteresis loops of the particle system in a wide temperature range ( ), we simultaneously determine the magnetic anisotropic field , the reduced remanence , and the coercive field in the whole temperature range below the Curie temperature. These complete sets of data allow us to quantitatively test the Stoner–Wohlfarth theory and the agreement between experiment and theory is good. [Copyright &y& Elsevier]