A large coercive field, HC =20 kOe, is obtained at room temperature in ε- Fe2 O3 nanoparticles embedded in a silica matrix, produced by sol-gel chemistry. The combination of a relatively high magnetic anisotropy together with the small saturation magnetization are responsible for this large HC. Upon cooling, a strong reduction of HC is observed at T∼100 K, which is accompanied by a drastic reduction of the squareness ratio MR MS. Neutron-diffraction measurements reveal the existence of a low-temperature magnetic transition to which the softening of this material can be ascribed. © 2005 American Institute of Physics.
|Journal||Journal of Applied Physics|
|Publication status||Published - 15 Aug 2005|