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The magnetization dynamics of a rectangular magnetic thin film are studied using micromagnetic simulations. The film is excited by an inplane external magnetic field that is perpendicular to the easy axis. The dynamics that govern the rotation of the magnetization were extracted assuming quasistatic equilibrium before the external field was changed. The power spectral density (PSD) of the time series, spatially averaged over the sensor geometry, reveal the existence of a fundamental precession frequency and an upper sideband. At a critical angle of rotation, the collision of edge domains causes the excitation of spin waves which appear as multiple peaks in the PSD. The process of collision and formation of domain walls causes the central portion of the sensor to switch abruptly between horizontal and vertical directions. The distance betwen the domain walls before collision becomes a measure of the quiescent state stability of the sensor. We also observe wall displacement waves along the edges of the domains using temporal snapshots of the precession frequency within a micromagnetic cell. Index Terms--Giant magnetoresistance, hysteresis, magnetic domains, magnetic recording.

Several studies are conducted to explain the various effects of temperature variation on the different magnetorestrictive properties of the Co[Al.sub.x][Fe.sub.2- x][O.sub.4] systems. The magnetorestriction, strain sensitivity and the other properties of the compounds are shown to be completely dependent on the temperature.

The variations in magnetization and magnetic anisotropy of [Ge.sup.4+]/[Co.sup.2+] cosubstituted cobalt ferrite with temperature are examined for a series of compositions [Co.sub.1+x][Ge.sub.x][Fe.sub.2-2x][O.sub.4]. The use of the Law of Approach model has given values of anisotropy coefficient [K.sub.1] that are lower than the correct values and this method cannot be used for estimating anisotropy accurately.

The effect of gallium substitution on the temperature dependence of magnetization, magnetocrystalline anisotropy and coercivity of Co[Ga.sub.x][Fe.sub.2-x][O.sub.4] (0

The effect of temperature variation on the magnetoelastic properties of the CoAlxFe2-xO4 system (for x=0.0, 0.2, 05, and 0.7) has been studied. Substitution of Al3+ for Fe3+ was found to lower the Curie temperature of the samples and to change the lattice parameter. The magnitude of peak to peak magnetostriction, strain sensitivity, magnetomechanical hysteresis, and relative contributions of λ111 and λ100 to the resultant magnetostriction were found to vary with temperature. The results show the possibility of tailoring the magnetoelastic properties of highly magnetostrictive cobalt ferrite at temperatures of interest by cation substitution. [ABSTRACT FROM AUTHOR]

The effect of temperature variation on the magnetoelastic properties of the CoAlxFe2-xO4 system (for x=0.0, 0.2, 05, and 0.7) has been studied. Substitution of Al3+ for Fe3+ was found to lower the Curie temperature of the samples and to change the lattice parameter. The magnitude of peak to peak magnetostriction, strain sensitivity, magnetomechanical hysteresis, and relative contributions of λ111 and λ100 to the resultant magnetostriction were found to vary with temperature. The results show the possibility of tailoring the magnetoelastic properties of highly magnetostrictive cobalt ferrite at temperatures of interest by cation substitution. [ABSTRACT FROM AUTHOR]

The temperature dependence of magnetic properties of a series of aluminium-substituted cobalt ferrite, with the general composition of CoAlxFe2-xO4 (x = 0, 0.1,0.2,0.5), has been studied. It was observed that the magnetization, at an applied field of μ0 H = 5 T and a temperature of 10 K, does not change significantly for small amounts of Al, then reduces sharply for larger amounts of Al. Magnetic hysteresis loops were measured over a field range of -5 T ≤ μ0H ≤ 5 Tat temperatures between 10 and 400 K. The high field regions of these loops were modelled using the Law of Approach to saturation, which can be used to calculate the magnetocrystalline anisotropy using its description of the processes of rotation of domain magnetizations against anisotropy and forced magnetization. It was found that the first-order cubic anisotropy of these materials decreased with increasing temperature. It was also observed that the anisotropy of these materials decreased with increasing Al-content at a given temperature. [ABSTRACT FROM AUTHOR]

The potential of CoAlx Fe2-xO4 (x = 0.1 to 0.9) for magnetomechanical stress sensor applications has been studied. It was found that the plot of magnetostriction against applied magnetic field changed shape as Al content increased. Furthermore, substituting with Al3+ resulted in the increase of the sensitivity of strain to applied magnetic field (dλ/dH)max. The maximum magnetostriction for the Al-doped (x = 0.1) was 34% lower than un-doped Co-ferrite but the (dλ/dH)max was 112% higher. The magnitude of magnetostriction obtained for Al-doped samples is still sufficient for stress sensor and actuator applications. Results were compared with those obtained for Ge-, Ga-, Cr- and Mn-doped Co-ferrites. It was found that in terms of improving strain response to applied field whilst maintaining significant amplitude of magnetostriction CoAlxFe2-xO4 has promising potential for magnetomechanical stress sensor applications. [ABSTRACT FROM AUTHOR]

The temperature dependence of magnetic properties of a series of aluminium-substituted cobalt ferrite, with the general composition of CoAlxFe2-xO4 (x = 0, 0.1,0.2,0.5), has been studied. It was observed that the magnetization, at an applied field of μ0 H = 5 T and a temperature of 10 K, does not change significantly for small amounts of Al, then reduces sharply for larger amounts of Al. Magnetic hysteresis loops were measured over a field range of -5 T ≤ μ0H ≤ 5 Tat temperatures between 10 and 400 K. The high field regions of these loops were modelled using the Law of Approach to saturation, which can be used to calculate the magnetocrystalline anisotropy using its description of the processes of rotation of domain magnetizations against anisotropy and forced magnetization. It was found that the first-order cubic anisotropy of these materials decreased with increasing temperature. It was also observed that the anisotropy of these materials decreased with increasing Al-content at a given temperature. [ABSTRACT FROM AUTHOR]

The temperature dependence of the magnetoelastic properties of the CoGaxFe2-xO4 system (for x = 0.0, 0.2, and 0.4) has been studied. It has been shown that increase in temperature resulted in reduced magnetostrictive hysteresis. For both CoGa0.2Fe1.8O4 and CoGa0.4Fe1.6O4, the measured magnetostriction amplitudes were higher at 250 K than at 150 K. It was also shown that the temperature stability of magnetostriction in CoGa0.2Fe1.8O4 is higher than that of the other compositions studiedwhich is important for sensor applications. The highest strain sensitivity was obtained for CoGa0.2Fe1.8O4 at 250 K. Results demonstrate the possibility of tailoring magnetomechanical properties of the material to suit intended applications under varying temperature conditions. [ABSTRACT FROM AUTHOR]