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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.

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]