• 한국초전도학회:학술대회논문집
• /
• v.16
• /
• pp.31-31
• /
• 2006

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.447-450
• /
• 1995

Using Boltzmaan equation by introducing the potential barrier scattering which buit by Hall-effect, a possible origin of giant magnetoresistance in multilayers is proposed. The calculated results may be well explain the giant magnetoresistance observed in multilayers.

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.451-455
• /
• 1995

The composition and thickness dependence and the ferromagnetic under- and overlayer effect on the magnetoresistance ratio and saturation field of the Co-Ag nano-granular films were investigated. The maximum magnetoresistance (23% at R.T.) in the as-deposited state was obtained in the $3000{\AA}$ $Co_{30} Ag_{70}$ bare alloy film. As the thickness of the alloy films decreased below $500{\AA}$, the MR ratio decreased because of the resistivity increase and the non-uniform film formation. We showed that the ferromagnetic over- and underlayer could reduce the saturation field of the nano-granular films via exchange coupling effect. The magnetoresistance and the saturation field of the $100{\AA}$ alloy film were 3.65 % and 2.85 kOe respectively and those of the under- and overlayered alloy films with $200{\AA}$ Fe were 3.3 % and 1.23 kOe respectively.

• Journal of the Korean Magnetics Society
• /
• v.18 no.1
• /
• pp.28-31
• /
• 2008

We studied the effect of easy magnetization axis orientation with respect to the strip direction by measuring the magnetoresistance(MR), the magneto-optic Kerr effect(MOKE), and real-time domain evolution. The five strips were patterned on a single chip with the easy axis orientation of each strip relative to the longitudinal direction by around $0^{\circ}$, $18^{\circ}$, $36^{\circ}$, $54^{\circ}$ and $72^{\circ}$, respectively. The overall shape of field dependent MR was mostly governed by the anisotropy magnetoresistnace. The relative change of the longitudinal MR was significantly increased with increasing angle between the easy axis and strip direction, whereas, the transverse MR variation rate was decreased with increasing angle. Several MR steps were observed during the magnetization reversal, and the simultaneous measurement of the MOKE and the domain images identified that the MR steps were associated with evolution of the oppositely directed magnetic domain.

• Journal of the Korean institute of surface engineering
• /
• v.32 no.1
• /
• pp.61-66
• /
• 1999

The Spin-dependent tunneling magnetoresistance (TMR) effect was observed in $NiFe/Al_2O_3$/Co thin films. The samples were prepared by magnetron sputtering in a system with a base pressure of $3\times10^{-6}$Torr. the insulating $Al_2O_3$layer was prepared by r.f. plasma oxydation method of a metallic Al layer. The ferromagnetic and insulating layers were deposited through metallic masks to produce the cross pattern form. The junction has an active area of $0.3\times0.3\textrm{mm}^2$ and the $Al_2O_3$layer is deposited through a circular mask with a diameter of 1mm. It is very important that insulating layer is formed very thinly and uniformly in tunneling junction. The ferromagnetic layer was fabricated in optimum conditions and the surface of that was very flat, which was observed by AFM. Tunneling junction was confirmed through nonlinear I-V curve. $NiFe/Al_2O_3$/Co junction was observed for magnetization behavior and magnetoresistance property and magnetoresistance property is dependent on magnetization behavior and magnetoresistance property and magnetoresistance property is dependent on magnetization behavior of t재 ferromagnetic layer. The maximum magnetoresistance ratio was about 6.5%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.11
• /
• pp.934-940
• /
• 2001

Magnetic properties were investigated for Si/SiO$_2$/NiFe(300 )/A1$_2$O$_3$(t)/Co(200 ) junction related with the parameters of $Al_2$O$_3$. Insulating $Al_2$O$_3$ layer was formed by depositing a 5~40 thick Al layer, followed by a 90~120s RF plasma oxidation in an $O_2$ atmosphere. Magnetoresistance was not observed for tunnel junction with 5~10 thick Al layer, but magnetoresistance was observed large for tunnel junction with 15~40 thick Al layer. Oxidation time did not largely influence magnetoresistance. Tunnel magnetoresistance effect depended on magnetization behavior of two ferromagnetic layers. Tunneling junction was confirmed through nonlinear I-V curve. In this work, tunneling magnetoresistance(TMR) up to 30 % was observed. This apparent TMR is an artifact of the nonuniform current flow over the junction in the cross geometry of the electrodes.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.2
• /
• pp.182-184
• /
• 2004

Fine $La_{2/3}Ca_{1/3}MnO_3$ nanocrystalline powders have been successfully prepared by modified citrate pyrolysis process. The obtained LCMO nanoscale grains have a mean particle size of about 30 nm under optimal treatment conditions. The particle size can be controlled by adjusting processing parameters, such as treatment temperature and calcination time. X-ray diffraction, SEM and magnetoresistance effect were employed to study the crystal structure, morphology and magnetic property of these nanosized powders. A novel MR effect (MR > 45% (0 K < T < 340 K)) at room temperature has been found.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1076-1079
• /
• 2001

An anolmalous magnetoresistance effect has been theoretically studied at very low temperatures for composite normal metal conductors. This anomalous behavior is due to transverse Hall currents in the composite which would result in increased losses and higher effective resistance for the composite conductor. In this paper, transverse current flow and effective resistance with Cu-Al conductor configuration were analyzed using FEM(finite element method) for predicting the Hall losses to be resulted in anomalous magnetoresistance effect. And they are plotted three dimensionally to be visualized.

• Journal of Magnetics
• /
• v.13 no.1
• /
• pp.11-18
• /
• 2008

This study examines a new macroscopic ferrimagnet, Co-TbN. This ferrimagnet, consisting of two metallic phases, Co and TbN, demonstrated the typical macroscopic ferrimagnet properties of a magnetic compensation point and a negative giant magnetoresistance (GMR). The Co-TbN system with 32% TbN composition showed 0.72% GMR in magnetic fields up to 8 kOe at room temperature and 9% GMR in 40 kOe at 250 K. In the Co-TbN system, GMR exhibited a different dependence on temperature from that of ordinary GMR materials whose negative magnetoresistance decreases with increasing temperature. In contrast to ordinary GMR materials whose negative magnetoresistance decreases with increasing temperature, the GMR effect in the Co-TbN system increased with increasing temperature, due to the increase of ferromagnetic alignment of the Co and TbN in the magnetic field caused by the decreased exchange coupling with increasing temperature.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.408-410
• /
• 1997

An anomalous magnetoresistance effect has been observed at very low temperatures for composite normal metal conductors. This anomalous behavior is due to transverse Hall currents in the composite which would result in increased $I^2R$ losses and a higher effective resistance for the composite conductor. In this paper, transverse current flow and effective resistance of Cu-Al double-strip was analyzed using finite element method for predicting the Hall losses to be resulted in anomalous magnetoresistance effect, and then be able to visualized.