• Journal of the Korean Magnetics Society
• /
• v.11 no.4
• /
• pp.163-167
• /
• 2001

The rotation of uniaxial anisotropy field of 700 ${\AA}$ 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 $^{\circ}C$. With increase of annealing temperature over 160 $^{\circ}C$, the film gets uniaxial anisotropy field again. An abrupt increase of H$\sub$c/ was observed with annealing temperature over 400 $^{\circ}C$. 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 $^{\circ}C$ magnetic annealing.

• Journal of the Korean Magnetics Society
• /
• v.7 no.5
• /
• pp.243-248
• /
• 1997

The effect of $O_2$ partial pressure on microstructure and soft magnetic properties of as-deposited Fe-Hf-O thin film alloys, which are produced by rf magnetron sputtering method in $Ar+O_2$ mixed gas atmosphere, are investigated. Saturation magnetization ($4{\pi}M_s$) of Fe-Hf-O film were decreased with increasing $O_2$ partial pressure, the best soft magnetic properties exhibit at $O_2$ partial pressure of 10%. With further increase of $O_2$ partial pressure, soft magnetic properties decreased continuously. The $Fe_{82}Hf_{3.4}O_{14.6}$ film with $P_{O2}=10%$ exhibits good soft magnetic properties with $4{\pi}M_s=17.7kG$, $H_c=0.7Oe$ and ${\mu}_ {eff}$ (1~100 MHz)=2,500, respectively. The addition of O is effective in grain refinement. In case of $P_{O2}=15%$, it is observed that $Fe_3O_4$ compound is formed and high frequency soft magnetic properties are decrease. The electrical resistvity($\rho$) of Fe-Hf-O film is increased with increasing $O_2$ partial pressure. Electrical resistivity of $Fe_{82}Hf_{3.4}O_{14.6}$ film was 5 times higher than that of the film without oxygen. Thus, it is considered that the good magnetic properties of $Fe_{82}Hf_{3.4}O_{14.6}$ film results from decreasing the $\alpha$-Fe grain size by precipitates (Hf and O), high electrical resistivity.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.10
• /
• pp.1849-1860
• /
• 1994

Domain wall dynamics in thin film of amorphous Rare Earth-Transistion Metal alloys were investigated using numerical integration of the Landau-Lifshitz-Gilbert equation. The thin film was divided into a two-dimensional square lattice ($30\times30$) of dipoles. Nearest-neighbor exchange interaction magnetic anisotropy, applied magnetic field, and demagnetiing field of interacting anisotropy, applied magnetic field, and demagnetizing field of interacting dipoles were considered. It was assumed that the film had perfect uniaxial anisotropy in the perpendicular direction and the magnetization reversal existed in the film. The time of domain wall creation and the thickness of the wall were investigated. Also the motion of domain walls under an applied field was considered. Simulation results showed that the time of domain wall creation was decreased significantly and the average velocity of domain wall was increased somewhat when the demagnetizing field was considered.

• Journal of the Korean Ceramic Society
• /
• v.43 no.2 s.285
• /
• pp.74-78
• /
• 2006

A non-integrated type noise filter on a Coplanar Waveguide (CPW) transmission line is demonstrated by using a highly resistive $Co_{41}Fe_{38}Al_{13}O_8$ nanogranular thin film with the dimensions of $4\;mm (\iota)\times4\;mm(\omega)\times0.1\;{\mu}m(t)$. The noise suppression characteristics are evaluated without placing an insulating layer between the CPW line and the magnetic thin film. The insertion loss is very low being less than 0.3 dB and this low value is maintained up to 2 GHz. At a ferromagnetic resonance frequency of 3.3 GHz, the power loss is very large and the degree of noise attenuation is measured to be 3 dB. This level of noise attenuation is still small for real applications; however, considering the small magnetic volume used in this work, further improvement is expected by simply increasing the magnetic volume and by integrating the magnetic thin film into the CPW transmission line.

• Journal of Magnetics
• /
• v.5 no.2
• /
• pp.44-49
• /
• 2000

Computer simulation of sensing current effects on the magnetic and magnetoresistance properties of a crossed spin-valve head is carried out. The spin-valve head has the following layer structure: Ta (8.0 nm)/NiMn (25 nm)/NiFe (2.5 nm)/Cu (3.0 nm)/NiFe (5.5 nm)/Ta (3.0 nm), and it is 1500 nm long and 600 nm wide. Even with a high pinning field of 300 Oe and a high hard-biased field of 50 Oe, the ideal crossed spin-valve structure, which is essential to the symmetry of the output signal and hence high density recording, is not realized mainly due to large interlayer magnetostatic interactions. This problem is solved by applying a suitable magnitude of sensing currents along the length direction generating magnetic fields in the width direction. The ideal spin-valve head is expected to show good symmetry of the output signal. This has not been shown explicitly in the present simulation, however, The reason for this is possibly related to the simple assumption used in this calculation that each magnetic layer consists of a single domain.

• Journal of Magnetics
• /
• v.17 no.2
• /
• pp.78-82
• /
• 2012

CoNiFe(CNF)/$BaTiO_3(BTO)$/CoNiFe(CNF) multilayered thin films were deposited on Pt/Ti/$SiO_2$/Si substrates by using pulsed laser deposition (PLD) system. We fabricated three different thin films of BTO, BTO/CNF and CNF/BTO/CNF for magneto-capacitor and studied their crystalline structure, surface and interface morphology, and magnetic and electrical properties. When three different structures of multilayered thin film were compared, magnetization of CNF/BTO/CNF thin films was decreased by magnetic and dielectric interaction. Also we confirmed that capacitance of CNF/BTO/CNF multilayered thin film was enhanced as being near tetragonal structure with increasing of c/a ratio because of atomic bonding at interface between BTO dielectric and CNF magnetic materials. Finally, we studied the change of the capacitance of CNF/BTO/CNF multilayered thin film with magnetic field for emergence of magnetocapacitance and suggested a possibility of enhanced capacitance.

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.528-532
• /
• 1995

Ferromagnetic resonance experiments have been used to investigate the magnetic properties of amorphous $Co_{89.5}Zr_{10.5}$ thin films deposited by DC magnetron sputtering method. In the thickness range from $350\;{\AA}$ to $3,200\;{\AA}$, measurements were carried out in a static magnetic field perpendicular and parallel to the film plane and in a conventional 9.44 GHz spectrometer at room temperature. The ferromagnetic resonance spectra by the field perpendicular to the film plane showed standing spin wave. The spacing and the relative intensities between the various spin wave resonance peaks are analysed considering surface magnetic anisotropy. The surface magnetic anisotropy constant ($K_{so},\;K_{sd}$) of amorphous $Co_{89.5}Zr_{10.5}$ thin films are $0.02\;erg/\textrm{cm}^2$ and $0.55\;erg/\textrm{cm}^2$ respectively regardless of the film thickness except for $3,200\;{\AA}$ film. In case of $3,200\;{\AA}$ these values are $0.46\;erg/\textrm{cm}^2$ and $0.55\;erg/\textrm{cm}^2$ respectively.

• Journal of the Korean Ceramic Society
• /
• v.43 no.2 s.285
• /
• pp.79-84
• /
• 2006

We studied the microstructure and magnetic property of the pulsed DC magnetron sputtered $Zn_{\0.8}Co_{0.2}O$ film as a function of substrate temperatures. The X-ray patterns of the $Zn_{\0.8}Co_{0.2}O$ film showed a strong (002) preferential orientation at $500^{\circ}C$. The films with a crystallite size of 23-35 nm were grown in the form of nano-sized structure and this tendency was remarkable with increasing substrate temperature. The UV-visible result showed that the $Zn_{\0.8}Co_{0.2}O$ film prepared above $300^{\circ}C$ has a high optical transmittance of over $80\%$ in the visible region. The absorption bands were observed due to sp-d interchange action by $Co^{2+}$ complex ion and dd transition in the region from 500 to 700nm. The resistivity of the film was below $10^{-1}\;\Omega-cm\;above\;300^{\circ}C$. The AGM analysis results for the all films showed the magnetic hysteresis curves of ferromagnetic nature. The low electrical resistivity and room temperature ferromagnetism of ZnCoO thin films 'deposited above $300^{\circ}C$ suggested the possibility for the application to Diluted Magnetic Semiconductors (DMSs).

• Journal of Magnetics
• /
• v.3 no.2
• /
• pp.55-63
• /
• 1998

Magnetic and magnetostrictive properties of amorphous Sm-Fe and Sm-Fe-B thin films are systematically investigated over a wide composition range from 14.1 to 71.7 at.% Sm. The films were fabricated by rf magnetron sputtering using a composite target composed of an Fe (or Fe-B) plate and Sm chips. The amount of B added ranges from 0.3 to 0.8 at. %. The microstructure, examined by X-ray diffraction, mainly consists of an amorphous phase in the intermediate Sm content range from 20 to 45 at.%. Together with an amorphous phase, crystalline phases of Fe and Sm also exist at low and high ends of the Sm content, respectively. Well-developed in-plane anisotropy is formed over the whole compositionrange, except for the low Sm content below 15 at.% and the high Sm content above 55 at %. As the Sm content increases, the saturation magnetization decreases linearly and the coercive force tends to increase, with the exception of the low Sm content where very large magnitudes of the saturation magnetization and the coercive force are observed due to the existence of the crystalline $\alpha$-Fe phase. The coercive force is affected rather substantially by the B addition, resulting in lower values of the coercive force in the practically important Sm content range of 30 to 40 at.%. Good magnetic softness indicated by well-developed in-plane anisotropy, a square-shaped hysteresis loop and a low magnitude of the coercive force results in good magnetostrictive characteristics in both Sm-Fe-B thin films. The magnetostrictive characteristics, particularly at low magnetic fields, are further improved by the addition of B; for example, at a magnetic field of 100 Oe, the magnitude of magnetostriction is -350 ppm in a Sm-Fe thin film and it is -470 ppm in a B containing Sm-Fe thin film.

• Journal of Magnetics
• /
• v.6 no.4
• /
• pp.129-131
• /
• 2001

In order to investigate the effect of the interface on GMR, [NiFe(25 ${\AA}$)/Cu(24${\AA}$)]$_2$/Si thin film was epitaxially grown on HF-treated Si (001) substrate using a DC magnetron sputtering method. Typical GMR effects could be observed in epitaxial film with a weak antiferromagnetic exchange coupling while non epitaxial film showed unsaturated and broad MR curves probably due to inter-diffusion between NiFe and Cu layers. Ferromagnetic resonance (FMR) experiment showed two distinct absorption peaks in all films. Each peak was revealed to come from each NiFe layer with different magnetic property. In FMR measurement very clear interface in epitaxial films could be confirmed by a lower value of line width (ΔH) and higher M$\sub$s/ of epitaxial film than those of non epitaxial films, respectively.