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The following structures are deposited under the conditions stated: (a) glass/Ru (X nm)/Co60Fe20V20(5 nm) and (b) glass/Ta(Y nm)/Co60Fe20V20(5 nm) at room temperature (RT), where each of X and Y is from 5 nm to 10 nm. The hysteresis loop of glass/Ru (X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) presents in-plane easy-axis magnetic anisotropy. The saturation magnetization (Ms) of glass/Ru(X nm)/Co60Fe20V20(5 nm) is decreased from 1490 emu/cm3 to 1050 emu/cm3 when the Ru thickness is increased. The maximum Ms of glass/Ru(5 nm)/Co60Fe20V20(5 nm) is about 1490 emu/cm3. The Ms of glass/Ta(Y nm)/Co60Fe20V20(5 nm) displays a concave-up feature. The maximum Ms of glass/Ta(10 nm)/Co60Fe20V20(5 nm) is about 1300 emu/cm3. The Ms varies with the Ru and Ta seed layer thicknesses due to various distances of spin-coupling interaction. In addition, the Hc values have very small ranges from about 1.2 Oe to 3.4 Oe in glass/Ru(X nm)/Co60Fe20V20(5 nm) and 1.0 Oe to 2.6 Oe in glass/Ta(Y nm)/Co60Fe20V20(5 nm), suggesting that the magnetic characteristic is soft magnetism owing to a low Hc and high Ms. The transmittance percentage (%) of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) is decreased from 16.5% to 7% and decreased from 16% to 12%, respectively, as the Ru and Ta thicknesses change from 5 nm to 10 nm, because a greater thickness and interface effect can inhibit the transfer of photon signals through the film, causing low transmittance. According to magnetic and optical performance, the optimal seed layer thicknesses of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) are 5 nm and 10 nm, which are suitable for magnetic-optical recording medium applications.

In this study, the maximum alternating current (AC) magnetic susceptibility (χac) and optimal resonance frequency (fres) of (a) glass/Ru (X nm)/Co60Fe20V20(5 nm) and (b) glass/Ta(Y nm)/Co60Fe20V20(5 nm) films at room temperature (RT) were investigated through low-frequency AC magnetic susceptibility (χac) measurement, where X and Y each ranged from 5 to 10 nm. The variation of the highest χac at the optimal resonance frequency (fres), at which the spin sensitivity is maximal, was examined using an experiment. The results indicated that χac decreased as the frequency was increased. The maximum χac of glass/Ru(9 nm)/Co60Fe20V20(5 nm) and glass/Ta(8 nm)/Co60Fe20V20(5 nm) was 20.6 × 10−3 and 15.5 × 10−3 at fres 100 Hz and 1000 Hz, respectively. The maximum χac of glass/Ru(9 nm)/Co60Fe20V20(5 nm) was 1.3 times larger than that of glass/Ta(8 nm)/Co60Fe20V20(5 nm). This indicated that the effect of the Ru seed layer is apparently suitable for low-frequency magnetic recording applications.

The thermal stability of FePdB thin films was studied using nonisothermal and isothermal analyses. X-ray diffraction (XRD) patterns indicated that Fe40Pd40B20 and Fe60Pd20B20 films with thicknesses in the range 25–75 A were amorphous, whereas Fe40Pd40B20 and Fe60Pd20B20 films with thicknesses in the range 100–200 A exhibited a nanocrystalline FePd (111) structure. The crucial glass forming ability index (γ and γm) was determined using the differential scanning calorimetry (DSC) results of amorphous FePdB films. The Kissinger formula was applied to calculate the activation energy (Q) of crystallization for determining the resistance of the films to crystallization. Thermal analysis showed that the thermal stability and incubation time of Fe40Pd40B20 are more favorable than those of Fe60Pd20B20.

In this investigation, the transmittance and electrical properties of NiFe thin films were measured under three conditions. NiFe thin films were sputtered on a glass substrate with a thickness ( t f ) from 300 A to 1500 A under the following conditions: (a) substrate temperature ( T s ) maintained at room temperature (RT), (b) post-annealing at T A =150 °C for 1 h, and (c) post-annealing at T A =250 °C for 1 h. Transmission electron microscopy (TEM) demonstrated that the NiFe film yielded a strong face-centered cubic (FCC) (1 1 1) selected-area-diffraction (SAD) pattern. A spectral analyzer was utilized to measure transmittance through various thicknesses. Post-annealing treatment promoted the growth of grains, yielding a large average grain size, and therefore a small transmittance. However, electrical measurements revealed that increasing the electron mobility reduces the resistivity ( ρ ) and sheet resistance ( R s ). At a thickness of 300 A with post-annealing 250 °C, the optimal maximum transmittance is 50%; the optimal ρ is 110 μΩ cm, and the optimal R s is 13 Ω/□. Accordingly, a 300 A-thick NiFe thin film with favorable electrical and optical properties can be utilized in the components of a magneto-optical recording medium.

This investigation experimentally studies the low-frequency alternating-current magnetic susceptibility ( χ ac ) of amorphous and nanocrystalline CoFeB films by measuring the magnetic field established by passing currents of various frequencies through such films of various thicknesses ( t f ). A CoFeB film is sputtered onto a glass substrate with t f from 100 A to 500 A under the following conditions: (a) As-deposited films were maintained at room temperature (RT) and (b) films were post-annealed at T A =150 °C for 1 h. The samples thus obtained are analyzed in a magnetic field that was generated by an alternating current (AC) at various frequencies from 10 Hz to 25,000 Hz. The experimental results demonstrate that the χ ac declines as the thickness of the as-deposited sample and the post-annealed sample ( T A =150 °C) increases because the lower coercivity ( H c ) of thinner CoFeB films is similar to a soft magnetic characteristic and is associated with a higher χ ac value. The best χ ac value is obtained at a thickness of 100 A under both conditions. The χ ac value of the post-annealed sample exceeds that of the RT sample at thicknesses from 100 A to 500 A because the magneto crystalline anisotropy of the post-annealed sample yields the highest χ ac value at the optimal resonance frequency ( f res ), at which the spin sensitivity is maximal. The X-ray diffraction patterns (XRD) of as-deposited CoFeB films reveal their amorphous structure. The XRD results for the post-annealed films include a main peak at 2 θ =44.7° from the body-centered cubic (BCC) nanocrystalline CoFe that indicated a (110) textured structure. Post-annealing treatment caused that the amorphous structure to become more crystalline by a thermally driven process, such that the χ ac value of the post-annealed sample exceeded that of the RT sample. This experimental result demonstrates that the χ ac value decreased as the thickness of the thin film increased. Finally, the CoFeB thin films had the best χ ac at low frequency ( χ ac value and the optimal f res of a 100 A-thick CoFeB thin film were 1.6 and 30 Hz, respectively, following post-annealing at T A =150 °C for 1 h, suggesting that a 100 A-thick CoFeB thin film that has been post-annealed at T A =150 °C can be utilized as a gage sensor and in transformer applications at low frequencies.

The Co/IrMn exchange-biasing phenomenon has been studied by employing the Si(1 0 0)/Ta/Co/IrMn/Ta samples. They were made by the sputtering method with the two cases listed below: (a) depositing without an in-plane field and (b) depositing with an in-plane field, h =1500 Oe. We have investigated their exchange-biasing field ( H ex ), coercivity ( H c ), and crystalline structure. From the electron-diffraction-ring patterns of transmission electron microscopy (TEM) pictures, it appears the Ta seed layer may induce the following effect: the Co layer is Hexagonal ( HCP ) and IrMn is face-centered cubic (FCC) with (1 1 1) texturing. In the case of (a), H ex is in general very small, while in the case of (b), H ex is on the order of 50-100 Oe.At room temperature H ex may reach a maximum when IrMn thickness t AF =90 to 110 A and then increases when t AF from 110 to 150 A. We conclude that the IrMn (1 1 1) structure is an important factor in governing the exchange-biasing field.