Anisotropy-induced quantum superparamagnet state in cobalt-ferrite nanoparticles at low temperatures

Influence of environment and grain size on magnetic properties of nanocrystalline Mn–Zn ferrite

“…It may be noted that magnetocrystalline component of the overall anisotropy is essentially independent of grain volume, though the overall/effective anisotropy increases with a decrease in crystallite size. Hsieh et al [22] reported that the overall anisotropy contribution for nanoparticles is about two to three orders of magnitude higher than that of coarsegrained bulk magnetocrystals. However, the strain component is expected to be significantly high for the high-energy ball-milled powders investigated in the present study.…”

On the structural, magnetic and electrical properties of sol–gel derived nanosized cobalt ferrite

“…The presence of cobalt ions in the tetrahedral sites coupled with the existence of multiple oxidation states of cobalt (Co 2+ /Co 3+ ) can give rise to altogether different structural and magnetic properties with respect to their bulk counterparts. It has been reported recently that spin disorder on the surface of the cobalt ferrite nanoparticles leads to interesting magnetic phenomena [13]. The electrical properties exhibited by ferrites in the micron regime are normally characteristic of hopping of electrons or holes or polarons between cationic sites [14].…”

Structural properties and magnetic interactions in Sr-doped Mg–Mn nanoparticle ferrites

“…It is seen that H r and DH decrease nonlinearly with Sr 2þ ion content x. The decrease of H r may be attributed to the effect of anisotropy, porosity, inhomogeneous demagnetization, saturation magnetization and the internal field [8,38,39]. The decrease of DH can be explained by existence of the divalent ions Fe 2þ , Mn 2þ , Sr 2þ and/or Mg 2þ among the octahedral B-sites which may affect the broadening of line width.…”

“…The lowest DH values prove the lowest loss at high frequency [38]. The relatively larger DH value for x ¼ 0.05 means high field absorption and more electric loss [39,40]. The Lande' factor (g) value equals 2.0023 for isolated free electron and changes in the solid environments.…”