High precision torque hysteresis measurements on fine particle systems

Paige, D.M.; Hoon, Steve R.; Tanner, B. K.; O’Grady, K.

doi:10.1109/tmag.1984.1063344

Cited by 30 publications

(5 citation statements)

References 9 publications

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“…The FMR spectra were measured at room temperature. The torque loss measurement was carried out using conventional method of Page et al 3 …”

Section: A Experimental Methodsmentioning

confidence: 99%

“…1,2 An anisotropy magnetic field H k is one of the important material constants that affects the character of a magnetic recording media. Many methods using a torque 3,4 or magnetization curve are used to measure H k . These methods are unable to eliminate the magnetic interaction, however, resulting in a systematic error to the value of H k .…”

Section: Introductionmentioning

confidence: 99%

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A method of measuring anisotropy field of polycrystalline thin-film media

Igarashi

Kambe

Yoshida

et al. 1999

Journal of Applied Physics

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High field ferromagnetic resonance measurements of the anisotropy field of longitudinal recording thin-film media High frequency permeability of patterned spin valve type thin films Ferromagnetic resonance ͑FMR͒ is used to measure the magnetic anisotropy field H k and its dispersion of poly-crystalline recording media. This method does not use any single crystal substrate. A high-intensity field is applied vertically to a sample surface to completely saturate the magnetization and a high-frequency ͑over 50 GHz͒ magnetic field is applied in the surface. An FMR simulator based on the Landau-Lifshitz-Gilbert equation confirms that the magnetic ͑exchange and/or magnetostatic͒ interactions have very little effect on the resonant frequency in the configuration used. The linewidth of the FMR spectrum is affected by the H k dispersion and damping constant. Methods using a torque or magnetization curve include magnetic interactions, resulting in a systematic error to the value of H k . This FMR method is applied to CoCrPt-alloy thin-film media with a Cr-alloy underlayer grown on a glass substrate. A conventional torque method is also used for comparison. The axis of hexagonal-close-packed Co magnetic grain is distributed at random in the surface. In an FMR measurement, external magnetic field is applied vertically to the surface up to 55 kOe for two frequencies ͑71 and 117 GHz͒. The obtained H k is 7.0Ϯ0.2 kOe, which is a little higher than the H k of 6.4 kOe estimated with the torque loss method. Important physical parameters that affect the recording performance are also estimated using the linewidth of FMR spectra for different frequencies with a micromagnetic simulation: H k dispersionϭ1.2Ϯ0.5kOe, Gilbert's damping constant ␣ϭ0.03Ϯ0.01, and a g valueϭ2.19Ϯ0.02.

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“…The FMR spectra were measured at room temperature. The torque loss measurement was carried out using conventional method of Page et al 3 …”

Section: A Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A method of measuring anisotropy field of polycrystalline thin-film media

Igarashi

Kambe

Yoshida

et al. 1999

Journal of Applied Physics

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“…For particulate media, the most widely used experimental techniques to determine the anisotropy constants are the switching methods, such as rotational hysteresis 1 and stiffness methods such as singular point detection techniques, 2 utilization of the law of approach to saturation, 3 and transverse susceptibility ( T ). 4 The main advantage of these methods is provided by the possibility of determining the anisotropy constant in polycrystalline samples under quite general conditions, disregarding the orientation or size distributions of the particles.…”

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confidence: 99%

Effect of the second-order anistropy constant on the transverse susceptibility of uniaxial ferromagnets

Spînu

Stancu

O’Connor

et al. 2002

Applied Physics Letters

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Reversal time of the magnetization of single-domain ferromagnetic particles with cubic anisotropy in the presence of a uniform magnetic field A generalized theoretical approach of the transverse susceptibility, T , in the case of uniaxial ferromagnets is presented. This advances the classical model of transverse susceptibility where only the first-order anisotropy constant, K 1 , is taken into account and makes possible the study of the influence of the second-order anisotropy constant, K 2 on the T curves. It is shown that additional Barkhausen jumps driven by higher-order anisotropy constants emerge more evidently in the field dependence of T making their detection much easier than from the hysteresis loop. Based on the obtained results, we propose a simple method to determine both, K 1 and K 2 independently from T experiments.

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“…The rotational hysteresis loss (W r ) was measured using a highly sensitive torque magnetometer to study H A and R h . W r falls to zero above the H A ; extrapolation of the decreasing W r yields an intercept with the abscissa that characterizes the largest anisotropy field of the materials [8]. films decreases as the temperature increases, as shown in Fig.…”

Section: Methodsmentioning

confidence: 85%