Large exchange bias effect in NiFe₂O₄/CoO nanocomposites

Giant Exchange‐Bias in Polyol‐Made CoFe2O4‐CoO Core–Shell Like Nanoparticles

“…Note that measured value of µ 0 H E = 365 mT on the composite particles is significantly higher than the best values recently reported on oxide‐based granular composites called “giant exchange‐bias” systems, like NiFe 2 O 4 ‐CoO, SrFe 12 O 19 @CoO, CoFe 2 O 4 @Co 3 O 4, and others summarized in Table SI‐1 in the Supporting Information. These results are very promising and make our engineered CFO‐CO composites particularly valuable as starting powder for the production of exchange‐biased oxide‐based consolidates.…”

Ni1–xZnxFe2O4@CoO (x = 0.25 and 0.50) Nanoparticles for Magnetic Resonance Imaging

“…The change in Larmor frequency has to be considered as Δ ω = M s γ 0 μ 0 3 , , where γ 0 denotes proton gyromagnetic ratio having a value of 2.67 × 10 8 rad s –1 ·T –1 , μ 0 refers to vacuum magnetic permeability with a value of 4π × 10 –7 T·mA –1 , and M s is saturation magnetization. r 2 is related to Δω and τ diff in MAR condition with volume fraction γ as r 2 = (16/45) γ,τ diff (Δω) 2 . − The motional averaging regime, , Δωτ diff < 1, defines the quick movement of water molecules during relaxation to expose water protons to a variety of magnetic fields as time goes on, and the motion averages the field that water protons experience. When the magnetic field being applied is lower than 1 T, these conventional quantum solutions characterizing electron–proton dipolar relaxation are highly effective in estimating relaxation rates.…”

“…We consider two different substitution concentrations of zinc atoms in Ni 1−x Zn x Fe 2 O 4 @CoO with Zn atom concentrations x = 0.25 and 0.5. The synthesis is governed by a coprecipitation technique 41 following a two-step synthesis procedure with few modifications. The required precursors are received from Zenith, India, and used without further purification.…”

“…r 2 is related to Δω and τ diff in MAR condition with volume fraction γ as r 2 = (16/45) γ,τ diff (Δω) 2 . 66−68 The motional averaging regime, 40,41 Δωτ diff < 1, defines the quick movement of water molecules during relaxation to expose water protons to a variety of magnetic fields as time goes on, and the motion averages the field that water protons experience. When the magnetic field being applied is lower than 1 T, these conventional quantum solutions characterizing electron−proton dipolar relaxation are highly effective in estimating relaxation rates.…”

On the first evidence of exchange-bias feature in magnetically contrasted consolidates made from CoFe2O4-CoO core-shell nanoparticles

“…To be effective, this phenomenon requires nanostructures with maximum interface contact. For this reason, it is mainly focused on thin films 2–6 and nanoparticles 7–10 where the interface between the F and AF phases is easier to control and to characterize. Therefore, it is particularly active in the technological fields involving multilayers or embedded nanoparticles (NPs) in thin films, such as those of magnetic recording heads 11,12 , magnetoresistive random access memories (MRRAM) 13–16 , magnetic sensors 17–19 and high storage capacity magnetic recording media 20 .…”