• Journal of the Korean institute of surface engineering
• /
• 제31권5호
• /
• pp.261-265
• /
• 1998

We investigated compositional separation of Co-23%Cr magnetic alloy thin films with varying film thicknesses. Saturation magnetization and magnetic microstructures were investigated using vibrating sample magnetometer (VSM) and scanning probe microscope (SPM), respectively. Saturation magnetization was as 700 emu/cc for films below 50 nm-thick, and changed to 430 emu/cc for the ones above 2000 nm-thick. This may be due to increment of molar volume of Cr-enriched phase as film thickness increases. The surface grain size in AFM (atomic force microscope) measurement becomes larger as film thickness increases. The MFM (magnetic force microscope) reveals that magnetic microstructure is changed from the fine spherical domains to the maze type domains as film thickness increases. We conclude that employing thickness of Co-22%Cr films below 50 nm is favorable for high density recording in order to enhance perpendicular saturation magnetization and SNR (signal to noise ratio).

• Journal of Magnetics
• /
• 제9권3호
• /
• pp.75-78
• /
• 2004

Magnetic transmission soft X-ray microscopy has been used to study element-specifically the magnetization reversal behavior of ${(Co_{84}Cr_{16})}_{87}Pt_{l3}$ alloy thin films with a lateral resolution of 35 nm. Our results indicate that the magnetization switching is carried out by a random nucleation process that can be attributed to the reversal of individual grains. We found evidence of a large distribution of the switching fields at the nanogranular length scale, which has to be considered seriously for applications of CoCrPt systems as magnetic high density storage materials.

• Journal of the Korean Magnetics Society
• /
• 제10권5호
• /
• pp.232-236
• /
• 2000

CoSm thin films with a Cr underlayer have received continuous attention as a potential material for a high density longitudinal magnetic recording media. In this study the Ax gas sputtering pressure effects on the magnetic properties of CoSm thin films, which were fabricated by using a dc magnetron sputtering machine, were investigated. The magnetic switching volume is especially important parameter to understand the thermal stability of the written information, magnetization reversal process and media noise. Therefore, in this paper the effects of sputtering pressure on the magnetic switching volume of CoSm thin films grown on Cr underlayer with the same sputtering conditions was studied. As the Ar sputtering pressure during sputtering of the CoSm magnetic layer increases from 5 to 30 mTorr, the measured switching volumes decreased from 9.0 to 5.2$\times$10$^{-18}$ cm$^3$. The calculated diameter of switching unit from V＊ was less than 22 nm, which satisfies the Sharrock's requirement on the thermal stability of the high density longitudinal magnetic recording media.

• Journal of Magnetics
• /
• 제2권3호
• /
• pp.76-85
• /
• 1997

Magnetic and magnetostrictive properties of Tb-Fe and Tb-Fe-B thin films are systematically investigated over a wide composition range from 40.2 to 68.1 at. % Tb. The films were fabricated by rf magnetron sputtering using a composite target which consists of an Fe plate and Tb chips. The microstructure, examined by X-ray diffraction, mainly consists of an amorphous phase and, at high Tb contents, a pure Tb phase also exists. A progressive change in the direction of anisotropy from the perpendicular to in-plane occurs as the Tb content increases and the boundary at which the anisotropy change occurs shifts significantly towards to higher Tb contents with the addition of B. The saturation magnetization exhibits maxima at the Tb contents of 42 and 48 at. % for Tb-Fe and Tb-Fe-B thin films, respectively, and it is decreased by the addition of B. The coercive force, measured in the easy direction, decreases monotonically with the Tb content. Excellent magnetostrictive characteristics, particularly at low magnetic fields, are achieved in both Tb-Fe and Tb-Fe-B thin films; for example, a magnetostriction of 138 ppm is obtained in a Tb-Fe-B thin film at a magnetic field as low as 30 Oe. The excellent magnetostrictive properties of the present thin films are supported by the equally excellent magnetic softness, the coercivity below 10 Oe and a typical squared-loop shape with the saturation field as low as 1 kOe. Due to the excellent low field magnetostrictive characteristics, the present Tb-Fe based thin films are thought to be suitable for Si based microdevices.

• The Korean Journal of Ceramics
• /
• 제1권2호
• /
• pp.91-95
• /
• 1995

Polycrystalline bismuth- and aluminum- substituted dysporsium and yttrium iron garnet (Bi2R3-xAlyFe5-yO12, R=Dy or Y, $0\leqx\leq3, \; 0\leqy\leq3$) films have been prepared by pyrolysis. The crystallization temperatures, the solubility limit of bismuth ions into the garnet phase, and magnetic and magneto-optic properties of the films have been investigated as a function of bismuth and aluminum concentration. It was found that the crystallization temperatures as a function of bismuth and aluminum concentration. It was found that the crystallization temperatures of these films rapidly decreased as bismuth concentration. It was found that the crystallization temperatures of these films rapidly decreased as bismuth concentration (x) increased up to x=1.5 and then remained temperatures of these films rapidly decreased as bismuth concentration (x) increased up to x=1.5 and then remained unchanged at x>1.5, whereas, showed no changes as aluminum concentration (y) increased up to y=1.0 and then gradually increased at y>1.0. The solubility limit of bismuth ions was x=1.8 when y=0 but increased to x=2.3 when y=1.0. It was demonstrated that the magnetic and magneto-optic properties of the dysprosium iron garnet films could be tailored by bismuth and aluminum substitution suitable for magneto-optic recording as follows. The saturation magnetization and coercivity data obtained for the films indicated that the film composition at which the magnetic compensation temperature became room temperature was y=1.2 when x=1.0. Near this composition the coercivity and the squareness of the magnetic hysteresis loop of the films were several kOe and unit, respectively. The Curie temperatures of the films increased with the increase of x but decreaed with the increase of y, and was 150-$250^{\circ}C$ when x=1.0 and y=0.6-1.4. The Faraday rotation at 633 nm of the films increased as x increased but decreased as y increased, and was 1 deg/$\mu\textrm{m}$ when x=1.0 and y=1.0. Based on the data obtained, the appropriate film composition for magneto-optic recording was estimated as near x=1.0 and y=1.0 or $BiDy_2AlFe_4O_{12}$.

• Journal of the Korean Magnetics Society
• /
• 제6권3호
• /
• pp.151-157
• /
• 1996

Magnetic properties and microstructures of FeTaNC thin films, which were deposited by magnetron reactive sputtering rrethod, were investigated as a function of $CH_{4}$ and $N_{2}$ gas partial pressures. Magnetic properties of FeTaNC films depended on total reactive gas pressure as well as $CH_{4}/N_{2}$ pressure ratios. For reactive gas partial pressures of 5~10 %, optimum magnetic properties were observed in the FeTaNC films with proper $CH_{4}/N_{2}$ ratio. On the other hand, at 15% of gas partial pressure, FeTaN and FeTaC films showed superior properties to FeTaNC films. Above 15%, the magnetic properties of films rapidly degraded due to an excess incorporation of C and/or N atoms. Excellent soft magnetic properties of 17 kG of Bs, 0.3 Oe of He, and 4000 of $\mu'$(at 5 MHz) were obtained in the FeTaNC films. High permeabilities of FeTaNC films could be explained by the Fe lattice distortion caused by N atoms, hence reduction of magnetic anisotopy. While precipitated TaN and TaC particles effectively supress the growth of $\alpha-Fe$ grains leading to a good soft magentic properties, FeN and FeC phases such as $Fe_3N$, $Fe_4N$, FexC have detrimental effects.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 1993년도 하계학술대회 논문집 B
• /
• pp.1143-1146
• /
• 1993

The magnetic properties of aluminium anodized film in which Co-Fe alloy electrodeposited are investigated with regard to the alloy composition of magnetic films. The electrodeposited Co-Fe particles are confirmed to be single phase Co-Fe alloys by X-ray diffractions. The coercive force as well as the magnetic anisotropy energy can be controlled by changing the composition of the alloy. Magneticfilms having high saturation magnetization and high coercive force were obtained.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.168-170
• /
• 2001

The NiCr is an important material for present thin-film resistor application owing to its low TCR and thermal stability. In this work, the NiCr thin films were deposited on corning glass substrate by reactive magnetron sputtering and the annealing at temperatures range from 300 to $500^{\circ}C$ for 20 min in vacuum. X-ray, AFM, $R_s$(surface leakage current) have been used to study the structural and electrical properties of the NiCr thin films. The high precision NiCr thin films resistor with TCR(temperature coefficient of resistance) of less then 10 ppm/$^{\circ}C$ was obtained under in in-situ annealing at $300^{\circ}C$ on Cr buffer layer substrate. It is clear that the NiCr thin-films resistor electrical properties are low TCR related with it's annealing and buffer layer condition. NiCr thin film resistor having a good thermal stability and low TCR properties are expected for the application to the dielectric material of passive component.

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.226-226
• /
• 2010

Microstructure, magnetic and transport properties of as-deposited electron-doped $La_{1-x}Ce_xMnO_3$ and hole-doped $La_{1-x}Ce_xMnO_3$ films prepared by pulse laser deposition, with x = 0.1 and 0.3, have been investigated. The microstructural analysis reveals that the $La_{1-x}Ce_xMnO_3$ films have a column-like microstructure and a strip-domain phase with a periodic spacing of about 3c, which were not found for the $La_{1-x}Ce_xMnO_3$ ones. At the same time, the experimental results manifest that there is no fundamental difference in the magnetic and the transport properties between electron- and hole-doped manganite films, except the appearance of ferromagnetic response in the low-doped $La_{0.9}Ce_{0.1}MnO_3$ film at temperatures above the Curie point. The observed magnetic behavior, typical for the Griffiths-like phase, for this film is explained by the percolation mechanism of the ferromagnetic transition and by the presence of strip-domain phase which stimulates the magnetic phase separation.

• Journal of the Korean Magnetics Society
• /
• 제5권5호
• /
• pp.601-605
• /
• 1995

Magnetic properties of FeTaN and FeTaC films deposited by DC magnetron reactive sputter were investigated, and correlated with their microstructures. The optimum magnetic properties of Hc : 0.25 Oe, Bs : 14.5 kG, and ${\mu}'$ : 4000 (5MHz) are observed in the $Fe_{78.8}Ta_{8.5}N_{12.7}$ film, and Hc : 0.25 Oe, Bs : 14.5 kG, and ${\mu}'$ : 2700 (5MHz) in the $Fe_{75.6}Ta_{8.1}C_{16.3}$ film. In both FeTaN and FeTaC films with minimum grain size show the best soft magnetic properties. Thermal stability of the soft magnetic properties of FeTaN is found to be higher than FeTaC for similar compositons. TaN and TaC particles form to retard the growth of $\alpha$-Fe grains. TaN particles in FeTaN show higher efficiency in retarding the grain growth during heat treatments resulting the higher thermal stability, compared to TaC particles in FeTaC films.