• Proceedings of the Korean Magnestics Society Conference
• /
• 2002.12a
• /
• pp.80-81
• /
• 2002

MR(magnetoresistance)은 물질의 저항이 자기장에 의해 변하는 물리적인 변화(physical MR)와 기하학적인 요소, 즉 sample의 모양과 contact의 크기 등에 의한 변화(geometric MR)의 합으로 나타낸다.[1] Physical MR은 자기장에 따른 비저항 또는 이동도(mobility)의 변화로 나타낼 수 있고, geometric MR은 로렌츠 힘에 의해 전류의 흐르는 방향이 변하면서 일어난다. 본 연구에서는 physical MR이 거의 없는 반도체(InAs)와 비교적 큰 physical MR을 가지는 반도체(HgCdTe)의 geometric factor를 고려한 MR의 향상에 대하여 연구하였다. (중략)

• Journal of the Korean Magnetics Society
• /
• v.5 no.3
• /
• pp.210-215
• /
• 1995

$Glass\Cr_{40\AA}\{[Cr_{10\AA}\NiFe_{50\AA}]}_N$ multilayers (number of layer N = 1, 2, 3, 4, 5, 6, 10) were made by dc magnetron sputtering under magnetic anisotropy of 200 G. Magnetoresistance curve MR(xx), MR(xy) were measured for the parallel and perpendicular current direction to external magnetic field. MR(xx) curves for the number of layer N=1, 5, 10 were almost became about zero percent, however the curves of other numbers appeared the phenomena of "positive magnetoresistance" that the resistance increased to external magnetic field, and the irregular and reversed curves in the vicinity of H=0 Oe.

• 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 Magnetics
• /
• v.3 no.1
• /
• pp.36-38
• /
• 1998

We measure the magnetoresistance (MR) of sputtered Permalloy ($Ni_{83}Fe_{17}$) films with external strains produced by piezoelectric tranducer actuators. We observe that the MR raito was increased by 2.3 times by a compressive strain of $3.5{\times}10^{-4}$ compared to that of the as-deposited film. Tensile strains and compressive strains reduced the MR ratio. These observations suggest that it is possible to tune the MR properties through the use of the external strains. We expect to apply the results for the multi-head magnetic recorders with selectively activated recording heads.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.355-358
• /
• 2000

Magnetoresistance changes of NiFe thin films were investigated as a function of deposition temperature. DC magnetron sputtering was employed to fabricate Ta/NiFe(t)/Ta thin films on Si(001) substrates with in-situ field or with no-field. The thickness(t) of NiFe films was a range of 4 to 15nm. Substrate temperature was a range of 30 to 400$^{\circ}C$. MR measurement was carried out as a function of angle $\theta$, between external field and current direction. MR ratio increased with increasing substrate temperature, also, max. MR ratio was observed in samples deposited at 300$^{\circ}C$. With increasing upto 400$^{\circ}C$, MR ratio was rapidly decreased in the case of thinner NiFe films. In non-field deposited NiFe films, both angle $\theta$=0, 90。, there was no significant change in MR curves. However, MR curves of in-situ field deposited NiFe films were different in both angles $\theta$=0 and 90。

• Journal of Magnetics
• /
• v.6 no.3
• /
• pp.83-85
• /
• 2001

The magnetoresistance properties of NiO/NiFe/Cu/NiFe spin valve film deposited on MgO(100) substrate with YBa$_2$$Cu_3O_7$(YBCO) film were investigated at room temperature and at 77 K. The magnetoresistance (MR) curves of the hybrid superconductor-magnetoresistor film structure showed an exchange coupling field of 300 Oe and an inverse magnetoresistance ratio of -6.5%. The magnetization configurations of the two magnetic layers in the NiO spin valve were antiparallel due to an increment in the conduction electron flow to superconductor YBCO film. This sample showed an inverse MR ratio.

• Journal of Magnetics
• /
• v.5 no.4
• /
• pp.135-138
• /
• 2000

In order to study the effect of the magnetic anisotropy on the giant magnetoresistance in a Co/Cu multilayered system, the angle dependent magnetoresistance (MR) was measured. The experimental results showed that the maximum MR ratio depends on the angle between the direction of the applied field and the easy axis. The angular modulation of the MR ratio can be explained by the alignments of the two 'effective' magnetization vectors that are bound to their own easy axes. Two maxima observed in MR loops at the second antiferromagnetic maximum are discussed in relation to the magnetic anisotropy, The simulated results under the assumption of the existence of two in-plane easy axes in the sample are compared with the experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1050-1053
• /
• 2001

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/HiO(300$\AA$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in 45$^{\circ}$Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) was shown in the range of about $\pm$50 Oe.

• Journal of the Korean Magnetics Society
• /
• v.8 no.4
• /
• pp.231-240
• /
• 1998

We investigated that the fabrication and reproducing signal characteristics of tri-layered magnetoresistance (MR) element for the high density magnetic thin film heads and sensors. Magnetoresistance curve of tri-layered MR element predicted by computer modeling was saturated above external field of -15 Oe~+22 Oe, and it was shifted to linearized region as large as 4 Oe. In the case of fabricated real device, magnetoresistance curve was saturated above external field of $\pm$15 Oe, and it was shifted to linearized region as large as 4 Oe. As shown in real device, MR response curve was in good agreement with the simulation results. As a result of experimental data of reproducing output signal in real device, it retained normal sinusoidal waveforms in 1~4 Oe external magnetic field. In this magnetic field region, the fabricated heads with tri-layered MR element can be operated with good reproduced characteristics. This will be beneficial to the use of efficient processes of manufacturing elements and the vacuum deposition techniques which control thin film properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.260-263
• /
• 2002

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in $45^{\circ}$ Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ was shown in the range of about ${\leq}{\pm}5$ Oe.