Tuning the thermal relaxation of transition-metal ferrite nanoparticles through their intrinsic magnetocrystalline anisotropy

Monodispersed ferrite nanoparticles of Fe₃O₄, MnFe₂O₄, and CoFe₂O₄ (near to 10 nm), were synthesized by organometallic synthesis, showing the same homogeneous chemical, morphological, and crystalline characteristics. The study and correlation of the thermal relaxation processes were analyzed through static and dynamic measurements. Due to the intrinsic chemical characteristics and magnetocrystalline anisotropy of the ferrite nanoparticles, the energy barrier can be tuned to a range between 1100 K ≤ E_B ≤7300 K, showing an alternative approach for tuning the magnetic dynamic properties, in contrast to the well-known mechanism through particle-size-effects. Specific loss power efficiencies were evaluated for the three ferrite samples. Comparing the three samples at the maximum ac frequency of ν = 10 kHz, MnFe₂O ₄ exhibits the single-peak maximum of loss with the value of 273 erg/s g at T = 65 K, whereas for the CoFe₂O₄, a maximum of 132 erg/-astr-temp·g (T = 217 K) was determined. A considerable drop in the efficiency was determined for the Fe₃O₄ nanoparticles, with the value of 20 erg/s g at T 43.5 K.