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Showing papers by "Seong-Cho Yu published in 1995"


Journal ArticleDOI
TL;DR: In this article, local structural changes during the crystallization process of initially amorphous Fe88Zr7B4Cu1 (at %) have been investigated by means of Mossbauer spectroscopy at room temperature.

19 citations


Journal Article
TL;DR: In this paper, a subgrain growth model was proposed to understand the observed grain structures in multilayers of Pd/(Pt/Co/Pt) modulated multilayer films.
Abstract: Pd/(Pt/Co/Pt) modulated multilayer films have been deposited on various substrates with Pd/Pt buffer layers. Films grown at different temperatures have very distinct magnetic properties and surface microstructures. Atomic force (AFM) and scanning tunneling (STM) microscopies studies of these films reveal that films deposited at room temperature have small grain structures with an average grain size of about 140 Å. However, much larger grains of about 1200 Å in size are observed in the films grown on buffer layers which were deposited at 500℃. These large grains are found to actually consist of smaller grains of about 170 Å in diameter. SQUID magnetic and Kerr hysteresis loop measurements indicate that multilayer films with large grains exhibit high magnetic coercivities of around 5 kOe. A subgrain growth model is proposed to understand the observed grain structures in the multilayers.

9 citations


Journal Article
TL;DR: In this article, the magnetic properties of amorphous Co-(895)Zr_(105) thin films deposited by DC magnetron sputtering method were investigated in a static magnetic field perpendicular and parallel to the film plane and a conventional 944 ㎓ spectrometer at room temperature.
Abstract: Ferromagnetic resonance experiments have been used to investigate the magnetic properties of amorphous Co_(895)Zr_(105) thin films deposited by DC magnetron sputtering method In the thickness range from 350 Å to 3,200 Å, measurements were carried out in a static magnetic field perpendicular and parallel to the film plane and in a conventional 944 ㎓ 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 (Kso, Ksd) of amorphous Co_(895)Zr_(105) thin films are 002 erg/㎠ and 055 erg/㎠ respectively regardless of the film thickness except for 3,200 Å film In case of 3,200 Å these values are 046 erg/㎠ and 055 erg/㎠ respectively

8 citations


Journal ArticleDOI
TL;DR: In this article, the effect of annealing temperatures on the spin wave excitations for the amorphous and nanocrystalline state of Fe/sub 76/Cu/sub 1/Nb/sub 3/Si/sub 14/B/sub 6/ alloys, observed from the low temperature magnetization curves and the spectroscopic splitting g factors, was reported.
Abstract: We report here on the effect of annealing temperatures on the spin wave excitations for the amorphous and nanocrystalline state of Fe/sub 76/Cu/sub 1/Nb/sub 3/Si/sub 14/B/sub 6/ alloys, observed from the low temperature magnetization curves and the spectroscopic splitting g factors. The temperature dependence of saturation magnetization was measured with a vibrating sample magnetometer and the SQUID magnetometer. Spectroscopic splitting g-values were estimated from ferromagnetic resonance experiments (FMR). The thermo-magnetization curve is found to obey Bloch's law, M/sub s/(T)=M/sub s/(0)(1-BT/sup 3/2/-CT/sup 5/2/). The spin wave stiffness constants were also observed from the preliminary results of the neutron inelastic scattering measurements. The spin wave stiffness constants obtained from two different experimental methods on the Fe/sub 76/Cu/sub 1/Nb/sub 3/Si/sub 14/B/sub 6/ alloys agree fairly well.

2 citations


01 Oct 1995
TL;DR: In this article, the effect of small addition of Nb on the electrical resistivity and Hall coefficient of the amorphous Fe_(83)Zr_7B_(10) alloy and annealed ones below the crystallization temperature were investigated.
Abstract: The effect of small addition of Nb on the electrical resistivity and Hall coefficient of the amorphous Fe_(83)Zr_7B_(10) alloy and annealed ones below the crystallization temperature were investigated, which has been considered to be suitable for high frequency core material. At room temperature, their resistivities ρ and the spontaneous Hall coefficients Rs are ~1.6 μΩm and ~ 3 × 10^(-8) ㎥/As, respectively. Rs and ρ are decreased with increasing temperature from 100 K to room temperature. Side-jump effect was adopted to analyze the effect of the small variation of concentration and annealing. The quantity of Rs/ρ² at room temperature, which is directly related to the electronic structure of the mother alloy, remained almost a constant except as Quenched one as it can be predicted from the side-jump effect. We suggested the temperature dependence of Rs/ρ² can be compared to Ms(T).

Journal ArticleDOI
TL;DR: In this paper, the magnetic properties of amorphous Fe/sub 83-x/Zr/sub 7/B/sub 10/Ni/sub x/ alloys annealed below the crystallization temperature were studied.
Abstract: We have studied the magnetic properties of amorphous Fe/sub 83-x/Zr/sub 7/B/sub 10/Ni/sub x/ alloys annealed below the crystallization temperature. Such materials are considered to have a potential for high frequency core material applications because of possibilities of obtaining high effective permeability and low coercive force. The addition of Ni content of approximately 0.5-1.5 at.% was found to be effective in improving the soft magnetic properties. The temperature dependence of magnetization measured by a SQUID magnetometer are found to be in good agreement with the spin wave theory. The spectroscopic splitting g values obtained by ferromagnetic resonance (FMR) experiments increase with increasing Ni content. The values of the spin wave stiffness increases from 62.7 meV /spl Aring//sup 2/ to 95.2 meV /spl Aring//sup 2/ with increasing the concentration of Ni. From these experimental results, the range of the exchange interaction are deduced.

Journal Article
TL;DR: Amorphous Co_(80+x)TM₁₂B_(8-x) (TM = Ti, Zr, Hf, Nb and x = 0, 2, 4 at%) alloys were prepared by single roll melt spinning technique Saturation magnetization of the amorphous ribbons was measured by SQUID and vibrating sample magnetometer from 5 to 800 K under applied fields up to 10 kOe Typical thermo-magnetization curves were observed and the average values of the spectroscopic splitting g factor were estimated from the
Abstract: Amorphous Co_(80+x)TM₁₂B_(8-x) (TM = Ti, Zr, Hf, Nb and x = 0, 2, 4 at%) alloys were prepared by single roll melt spinning technique Saturation magnetization of the amorphous ribbons was measured by SQUID and vibrating sample magnetometer from 5 to 800 K under applied fields up to 10 kOe Typical thermo-magnetization curves were observed and the average values of the spectroscopic splitting g factor were estimated from the ferromagnetic resonance curve For all the amorphous alloys studied here the saturation magnetization in the temperature range 5 K up to about 03Tc can be described by the Bloch relation: Ms(T) = Ms(0)(1-BT^(3/2)-CT_(5/2)) From the values of Ms(0), B and spectroscopic splitting g factor the spin wave stiffness constants were calculated

Journal Article
TL;DR: In this article, the temperature dependence of spin wave mode separation in amorphous Co-895)Zr 105 thin film has been investigated at temperatures between 100 K and 300 K.
Abstract: The temperature dependence of spin wave mode separation in amorphous Co_(895)Zr_(105) thin film has been investigated at temperatures between 100 K and 300 K The magnetization and the spectroscopic splitting factor were obtained for the main resonance mode in parallel and perpendicular magnetic field △H₂-₃, the difference between resonance field of mode 2 and the resonance field of mode 3, increases with decreasing temperature The linewidth increases for all the modes with decreasing temperature Especially in mode 3 it increases rapidly below 200 K This phenomenon could be caused by the increase of exchange stiffness constant or the decrease of surface magnetic anisotropy constant with decreasing temperature

Journal ArticleDOI
TL;DR: Amorphous Co82TM12B6 (TMTi, Zr and Hf) alloys were prepared by rapid quenching technique and the saturation magnetization of the amorphous ribbons was measured by SQUID and vibrating sample magnetometers from 5 to 800 K under applied fields up to 10 kOe as mentioned in this paper.