The Mn80/Ir18.1/Pt1.9/ exchange bias layers (EBLs), which have a small amounts of Pt, exhibit a high value of Hex/. The Si/Ni-Fe/Mn80/Ir18.1/Pt1.9/ EBL shows the largest Hex/ of 187 Oe, which is equivalent to a exchange energy (Jex/) of 0.146 erg/cm. Mn80/Ir18.1/Pt1.9/ EBLS are estimated to have blocking temperature of about 250 , which is higher than those of Mn-Ir EBLs and Mn-Ir-Pt EBLs with higher Pt contents. This result implies that a little addition of Pt element promotes thermal stability in the Mn-Ir-Pt EBLs. The chemical stability of Mn-Ir-Pt EBLs was characterized by potentiodynamic test, which was performed in 0.001 M NaCl solution. The current density of Mn-Ir-Pt films was gradually reduced with increasing Pt content. The present results indicate that the Mn-Ir-Pt with a small amount of Pt is suitable for an antiferromagnetic material for a reliable spin valve giant magnetoresistance device.

The effect of H content in Ar sputtering gas on exchange coupling field(H) for NiFe/FeMn interface was studied. When NiFe layer of Si(100)/Ta(50 )/NiFe(60 )/FeMn(250 )Ta(50 ) was deposited at 8% H in sputtering gas, the maximum exchange coupling field(H) and minimum coercivity(H) were obtained. When Si(100)/Ta(50 )/NiFe(60 )/FeMn(250 )/NiFe(70 )/Ta(50 ) was deposited at 5% H in sputtering gas, the maximum exchange coupling field(H) of 148 Oe was obtained. The (111) preferred orientation and grain size of underlayer NiFe were increased and the internal stress was reduced by H in sputtering gas. And the (111) preferred orientation and grain size of FeMn layer were also increased.d.ased.

Recently many studies on manganese oxides LnAMnO(Ln=La, Pr, Nd lanthannide; A=Ca, Sr, Ba, Pb +2 ions) reported CMR properties. CMR have been also found in chalcogenide spinels. We have investigated that Ni ion substitutions for Fe ion have effects on CMR properties in chacogenide spinels NiFeCrS. It was found that with increasing Ni concentration Jahn-Teller distortion was strengthened and Curie temperature T was increased. CMR properties could be explained with Jahnl-Teller effect, half-metallic electronic structure, and the alignment of magnetic domain due to the strong magnetic field, which is different in that double exchange interactions dominate CMR properties in manganese oxides.

Rheological characteristics of Sm-Co type plastic magnet compound for powder injection molding process were investigated with the variation of the magnetic powder size, their relative contents and volume fraction using the mixture of fine and coarse powder. Shear viscosity of Sm-Co type compound was decreased with increasing the size of coarse powder due to the increase of powder packing density. However, the smaller the average size of fine powder resulted in the higher viscosity of compound due to the increase of agglomeration force. In case of mechanically milled Sm-Co type powder, the viscosity of compound with the mixture of coarse powder of 125∼75 ㎛ and fine powder of average size of 4.9 ㎛ greatly depends on their relative contents and shows a minimum value at the 60 % coarse powder fraction. This means that the compound shows a maximum packing density at the 60% coarse powder fraction. Compound viscosities satisfied well the rheological model with the volume fraction of magnetic powder, and maximum volume fraction of magnetic powder in Sm-Co type compound for powder injection molding was about 66%.

The rotation of uniaxial anisotropy field of 700 thick sputtered NiFe thin film due to magnetic annealing was investigated. NiFe film was annealed in a magnetic field which is perpendicular to the initial induced uniaxial anisotropy field. The NiFe film becomes nearly isotropic after 1 hour annealing at 160 . With increase of annealing temperature over 160 , the film gets uniaxial anisotropy field again. An abrupt increase of Hc/ was observed with annealing temperature over 400 . The X-ray diffraction analysis and Auger electron spectroscopy with Ar ion etching showed extensive grain growth in NiFe film with (111) texturing and interdiffusion with adjacent Au electrode layer by 400 magnetic annealing.

Co-Zn ferrite thin films grown on thermally oxidized silicon wafers were fabricated by a sol-gel method. Magnetic and structural properties of Co-Zn thin films were investigated by using x-ray diffractometer (XRD), atomic force microscopy (AFM), auger electron spectroscopy (AES) and a vibrating sample magnetometer (VSM). Co-Zn ferrite thin films annealed at 400 presented have only a single phase spinel structure without any preferred crystallite orientation. Their surface roughness of Co-Zn ferrite thin films was shown as less than 3 nm and the grain size was about 40 nm for annealing temperatures over 600 . A moderate saturation magnetization of Co-Zn ferrite thin films for recording media was obtained in this study and there is no significant difference of their magnetic property with those external fields of parallel and perpendicular to planes of the films. The maximum value of the coercivity was obtained as 1,900 Oe for Co-Zn ferrite thin film annealed at 600 .

The effects of heat-treatment with magnetic or non-magnetic field on magnetic properties of gas-atomized MPP dust cores subjected to various cooling processes after annealing were investigated. Upon magnetic-field annealing, ac permeability and core loss decreased with the increase of cooling rate, which were attributed to the generation of inhomogeneous internal stress and anomalous eddy current loss, respectively. It was not observed the formation of ordered phase and the related change in magnetic properties at the cooling stage for MPP dust cores. In MPP alloys, magnetic anisotropy was easily induced through the directional order, and permeability and core loss were changed under the conditions of low cooling rate and magnetic annealing.