• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.224-230
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• 1998

The relationships between R-H curves of gaint magnetoresistance (GMR) spin valve trilayer films and M-H curves of each magnetic layer consisting of the trilayer films were analyzed and simple formula representing the relations between the curves were suggested for theoretical analysis and study of magnetoresistance (MR) in those films, especially where the MR is from the difference of coercivity. Using two kinds of NiFe/Cu/Co films, which had been deposited on Cu(50 $\AA$)/Si(111, 4$^{\circ}$ tilt-cut) and Cu(50 $\AA$)/glass, R-H and M-H curves were measured and compared with the calculated ones, which were obtained by appying the M-H curves of single NiFe and Co films, deposited on the same substrates, to the previously reported single-domain and multi-domain models. The calcuated ones were well consistent with the measured ones and the suggested simple relationships between R-H and M-H curves are thought to be very useful for the deep understanding of MR behavior and the reasonable approach to improve MR properties in GMR spin valve trilayer films.

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

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.71-72
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• 2013

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.29-33
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• 1993

Magnetoresistance was studied for the ferromagnetic tunneling junction in $Permalloy/Al_{2}O_{3}/Co$ prepared by evaporation in a vacuum of $1{\times}10^{-6}$Torr. We measured voltage-current characteristic and magnetic valve effect of prepared ferromagnetic tunneling junction sample. We investigated field-dependency of tunnel resistance by Wheat-stone bridge method and measured magnetic hysteresis curve by vibrating sample magnetometer. The tunneling is confirmed by measuring voltage-current characteristic. The hysteresis curve of magnetoresistance corresponds well with that of magnetization. The magnetoresistance ratio ${\Delta}R/R$ is 0.6% at room temperature.

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

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.340-346
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• 1994

Change in the electrical resistance of artificial superlattice under two magnetic fields-the main and the secondary magnetic field-has been studied with respect to each magnetic field strength in (200) textured Co/Cu artificial superlattice. When the two magnetic fields were applied in the same direction, lateral shift of the magnetoresistance curve occurred, while splitting phenomenon of the maximum resistance appeared when the two magnetic fields were applied at the right angle. When the angle between the two magnetic fields became $45^{\circ}$ shifting as well as splitting occurred in the magnetoresistance curve. This magnetoresistance behavior with double magnetic fields in the artificial superlattices could be explained with the macroscopic spin alignment model newly suggested in this work.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.98-103
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• 2013

The magnetic easy axis of the ferromagnetic layer for the dual-type GMR-SV (giant magnetoresistance-spin valve) having NiFe/Cu/NiFe/IrMn/NiFe/Cu/NiFe multuilayer structure controlled by the post annealing treatment. The magnetoresistive curves of a dual-type IrMn based GMR-SV depending on the direction of the magnetic easy axis of the free and the pinned layers are measured by the different angles for the applied fields. By investigating the switching process of magnetization for an arbitrary measuring direction, the optimum annealing temperature having a steady and isotropy magnetic sensitivity of 2.0 %/Oe was $105^{\circ}C$. This result suggests that the in-plane orthogonal magnetization for the dual-type GMR-SV film can be used by a high sensitive biosensor.

• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.228-231
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• 2004

We have studied local magnetization reversal and magnetic properties induced by Laser annealing method in the strip-patterned Ta/NiFe/FeMn/Ta and Ta/NiFe/FeMn/NiFe/Ta multilayers fabricated by ion-beam deposition. The films were exposed to the emission of the DPSS (Diode Pumped Solid State, Nd:YAG) laser under 600 G. The laser beam intensity increased up to 440 mW. When the laser illuminated the patterned film with the power of above 200 m W, the intensity of MR peak located in +87 Oe shrunk. A new MR peak was generated at -63 Oe. When the laser power is 400 mW, the location of positive MR peak(H$\sub$ex/) was changed slightly from +87 Oe to +76 Oe, and the MR ratio was decreased from 0.9% to 0.1 %. On the other hand, the new (negative) MR peak shifted from -63 Oe to -80 Oe, with the MR ratio increased up to 0.3%. As the illuminated area expanded, the intensity of opposite MR peak increased and it of negative MR peak decreased. This proved that the local reversal of exchange biasing should be realized by laser annealing.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.1-6
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• 1996

To simulate the characteristics of magnetic exchange coupling at the interface of MR/TbCo thin films, the directions of magnetizations were calculated by minimizing energy in the films. Newton method and Gauss-Seidel method were used. The width of M-H curve increased with TbCo anisotropy constant, and with the thickness of the transition region of TbCo layer. Hysteresis loop width became extremely narrow (less than 10 Oe of coercivity), when the TbCo transition region length was $400\;\AA$. Also the hysteresis loop of films with low interfacial exchange coupling constant was similiar to that of short transition region length. When interfacial exchange coupling constant was 1/100 of perfect coupling, hysteresis loop showed a coercivity of less than 10 Oe. Comparing the measured hysteresis loop of a fabricated sample with that of simulated one, exchange coupling con¬stant could be estimated.

• Journal of the Korean Magnetics Society
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• v.5 no.6
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• pp.963-967
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• 1995

Ultra thin layers of NiFeCo or NiFe were inserted at the interfaces of Ni and Cu to form a multilayer structure. In case of inserting a NiFe layer, the magnetoresistance was about 6%, the saturation magnetic field was 50 Oe and the hysteresis of R-H (resistance-magnetic field) was very small. In case of inserting a NiFeCo layer, the magnetoresistance increased to about 7% but the saturation magnetic field and hysteresis were also increased. The increase of the output under biased magnetic field was much larger in case of inserting a NiFe layer because of relatively smaller hysteresis in R-H behavior.