On the Magnetocrystalline Anisotropy of NiCo Ferrites

Abstract

The magnetocrystalline anisotropy of Co,Nii-, F%OI f Y is measured at room temperature by torque measurements. It is found that an additional couple caused by the anisodropy of the magnetization must be taken into account in the determination of the magnetocrystalline constants. For the ( 100)-plane is found that the magnetocrystalline anisotropy increases nearly linearly with the Co-content. The constants k, of the anisotropy of the magnetization also increase linearly a t low Co-additions, but a t higher Co-concentrations the increase is less than linear. Measurements in the (111)-plane show a marked dependence of Lmax on the magnetic field strength. Attempts to find the values of the constants by extrapolation prove unsuccesful.Die magnetische Kristallanisotropie wurde bei Raumtemperatur im System Co,Nil --2: Fez-0 4 + y mittels Drehmomentenmessungen untersucht. Es zeigte sich, daB sich dem durch die Kristallanisotropie bewirkten Drehmoment ein zusiitzliches, durch die Anisotropie der Yagnetisierung hervorgerufenes Drehmoment uberlagert. Fur die (100)-Ebene wurde gefunden, daO die Kristallanisotropie nahezu linear mit dem Co-Gehalt ansteigt, wiihrend die Konstante k, der Anisotropie der Magnetisierung bei geringen Co-Zusiitzen ebenfalls linear, bei hoheren Co-Gehalten weniger stark anwiichst. Messungen in der (111)-Ebene zeigten eine starke Feldstitrkeabhingigkeit der maximalen Drehmomente, so daO die Restimmung der Konstanten unmoglich war.

Magnetostatic Interactions in Self-Assembled CoxNi1–xFe2O4/BiFeO3 Multiferroic Nanocomposites

“…For bulk ceramic CNFO with 0 ≤ x ≤ 0.8 the lattice parameter varied approximately linearly with increasing Co concentration x. The saturation magnetization increased with x superlinearly in bulk ceramic Co x Ni 1– x Fe 2 O 4 and approximately linearly in nanocomposites and nanoparticles. − The magnetocrystalline anisotropy increased linearly with x measured in the range 0 ≤ x ≤ 1 and 0 ≤ x ≤ 0.12 …”

“…The saturation magnetization increased with x superlinearly in bulk ceramic Co x Ni 1−x Fe 2 O 4 30 and approximately linearly in nanocomposites 31 and nanoparticles. 32−34 The magnetocrystalline anisotropy increased linearly with x measured in the range 0 ≤ x ≤ 1 24 and 0 ≤ x ≤ 0.12. 35 Nanocomposite CNFO−BFO films were deposited on single-crystal (001) STO substrates from BFO, CFO, and NFO targets using pulsed laser deposition (PLD).…”

“…The spinel pillars in this experiment were made with composition Co x Ni 1– x Fe 2 O 4 (CNFO) varying between CFO and NFO. CFO has magnetocrystalline anisotropy K 1,CFO = (1.8 to 6.5) × 10 6 erg cm –3 , whereas K 1,NFO = −0.7 × 10 5 erg cm –3 . Moreover, CFO has a much higher magnetostriction, λ 001,CFO = (−250 to −590) × 10 –6 , compared to λ 001,NFO = −45.9 × 10 –6 .…”

Properties of cobalt ferrites grown by chemical transport

“…The shape of g(xeff) may differ in the case of cobalt ferrite. The latter interpretation is supported moreover by the results of magnetic moment measurements in cobalt ferrite grown by flame fusion [23] which yielded approximately 86 c.g.s. units g-l (241, a value close to that of this paper.…”