• Journal of the Korean Magnetics Society
• /
• v.5 no.4
• /
• pp.261-268
• /
• 1995

In order to investigate the origin of the asymmetric magnetization reversal effect, we studied the variation of magnetic hysteresis loops with the alloy composition in amorphous ferromagnetic alloy ribbons of ${(Fe_{1-x}Co_{x})}_{75}Si_{10}B_{15}$ system annealed at $380^{\circ}C$ for 16 hours in a zero field condition. The asymmetric magnetization reversal effect developed more strongly in amorphous ribbons having two metallic components than in ribbons having a single metallic component. The effect developed more strongly in ribbons showing a smaller value of the saturation mag¬netostriction. The development of the asymmetric magnetization reversal effect was affected by the ratio of two metallic components as well as the magnitude of the saturation magnetostriction.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1994.03a
• /
• pp.38-39
• /
• 1994

• Journal of Magnetics
• /
• v.14 no.1
• /
• pp.36-41
• /
• 2009

Magneto-optical Kerr effect (MOKE) magnetometry was used to investigate magnetization reversal dynamics in 30-nm NiFe/15-nm FeMn, 15-nm FeMn/30-nm CoFe bilayers, and 30-nm NiFe/(2,10)-nm FeMn/30-nm CoFe trilayers. The in-plane magnetization components of each ferromagnetic layer, both parallel and perpendicular to the applied field, were separately determined by measuring the longitudinal and transverse MOKE hysteresis loops from both the front and back sides of the film for an oblique incident s-polarized beam. The magnetization of the FeMn/CoFe bilayer was reversed abruptly and symmetrically through nucleation and domain wall propagation, while that of the NiFe/FeMn bilayer was reversed asymmetrically with a dominant rotation. In the NiFe/FeMn/CoFe trilayers, the magnetic reversal of the two ferromagnetic layers proceeded via nucleation and domain wall propagation for 2-nm FeMn, but via asymmetric rotation for 10-nm FeMn. The exchange-biased ferromagnetic layers showed the magnetization reversal along the same path in the film plane for the decreasing and increasing field branches from transverse MOKE hysteresis loops, which can be qualitatively explained by the theoretical model of the exchange-biased ferromagnetic/antiferromagnetic systems.

• Journal of the Korean Magnetics Society
• /
• v.5 no.4
• /
• pp.251-260
• /
• 1995

It has been reported that Co-based amorphous ferromagnetic alloys annealed in a small magnetic field develop a reproducible, asymmetric hysteresis loop. If the direction of the field during annealing is regarded as +, the magnetization reversal from - to + is smooth and reversible, with its slope determined by the demagnetizing field of the sample. This phenomenon is called the asymmetric magnetization reversal (AMR). The shape of the hyster-esis loop depends sensitively on the condition during the anneal and the alloy composition. Here, we report on the effect of the annealing temperature and time on AMR in a zero magnetostrictive ferromagnetic amorphous alloy. The AMR effect develops in a very short time at a reasonably high temperature, but is stabilized by annealing for a prolonged time.

• Proceedings of the KIEE Conference
• /
• 2008.10c
• /
• pp.38-40
• /
• 2008

Distribution of Permanent magnet used in the spindle motor on the ODD is arranged by magnetizer. In general, permanent magnet is putted between yoke and back yoke of magnetizer so that symmetric magnetization distribution. But the magnet has unsymmetric magnetization distribution because of eccentricity of the yoke in mass production. So, in this paper we discuss the effect of asymmetric magnetization distribution on back EMF and cogging torque of the spindle motor.

• Journal of Magnetics
• /
• v.11 no.2
• /
• pp.70-73
• /
• 2006

The magnetization angle and thickness dependence of magnetic anisotropy in the exchange-biased [Pd/Co]${\times}$5/FeMn multilayers with an out-of-plane anisotropy were investigated to determine the origin of perpendicular exchange biasing. As the Co thickness increased to 1.5 nm in the [Pd(0.8 nm)/Co(t)]${\times}$5/FeMn(120 nm) films, the hysteresis loops were converted from square loops at a thin Co (<0.4 nm) to complicated round ones at a thick Co. The irregularly asymmetric step (IAS) at the left top of the loop appeared in the loop of the 0.6-nm Co film due to an inhomogeneity in the exchange anisotropy. As the Pd thickness increased to 1.6 nm, the step disappeared, and the perpendicular magnetic anisotropy was maximized in the Co thickness between 0.6 and 0.9 nm. The conversion of the magnetization loop along the magnetization angle coincided with the equation $H_{(eff)}=H_o\;cos{\theta}$. The IAS of the 0.8-nm Pd film disappeared after thermal annealing up to $200^{\circ}C$ under an external magnetic field.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2003.08a
• /
• pp.141-141
• /
• 2003

• Proceedings of the Korean Magnestics Society Conference
• /
• 2004.06a
• /
• pp.48-49
• /
• 2004

• Journal of the Korean Magnetics Society
• /
• v.15 no.2
• /
• pp.72-75
• /
• 2005

The profiles of the second-order higher harmonics during B-H hysteresis loop have been measured as functions of the tensile stress in grain-oriented $3.2{\%}$ Si steels. The observed harmonics profiles have been analyzed in terms of the nonlinear, asymmetric magnetization which reflects the domain reorientation under the field. The field interval of the second-order higher harmonics is related to the nucleation and annihilation fields and a measurement method for the magnetostriction is proposed using the harmonics profiles under tensile stress.

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.579-582
• /
• 1995

The use of amorphous magnetic alloys as tags or targets in electronic article surveillance systems such as antishoplifting desvices is briefly reviewed. Improved tags became possible with the discovery in 1988 of asymmetric magnetization reversal (AMR) in certain amorphous alloys annealed in applied field approximately equal to the earth's field. These asymmetric hysteresis loops are highly unusual, if not unique, and so greatly diminish the probability of false alarms in a detection system. furthermore, the jump field Hj, which is the coercive field in negative applied fields, can be controlled over a useful range by controlling the field applied to the sample during annealing. By applying several tags to an object, each with a different jump field, it is possible to identify the object with a numeric code that can be remotely read by nonoptical means.