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The high-frequency characteristics of the RF integrated inductors with antiferromagnetic/ferromagnetic (AF/F) multilayers (MLs) are studied. Each AF layer is 8-nm IrMn and F is [Co.sub.50] [Fe.sub.50] with a 200-nm splitting into N = 1 to 5 repeats of MLs. This exchange coupled {IrMn/CoFe(d nm)}[sub.N] MLs are deposited on top of the two-port inductors with five-turn square spiral coils, a dimension of 100 [micro]m x 100 [micro]m and line/space of 5 [micro]m/2 [micro]m. The inductor surface and magnetic layer is separated by 1-[micro]m-thick Si[O.sub.2]. The enhancement of inductance ([DELTA]L) is 20% compared to an air-core of the same coil size. The resonance peak gradually shifted to a higher frequency with increasing N, and reached at a maximum of 4.3 GHz when N = 5. This is in good agreement with our magnetic data which revealed that the anisotropy field ([H.sub.k]) and ferromagnetic resonance frequency ([f.sub.FMR]) of {IrMn/CoFe(d nm)} [sub.N] MLs are increased with increasing N. The quality factor, Q is improved by 6.8% at 1.5 GHz for the {IrMn/CoFe(40 nm)}[sub.N=5] integrated inductors compared to air-core inductors. Index Terms--Antiferromagnefic (AF), exchange coupling, ferromagnetic resonance (FMR), frequency response, radio-frequency (RF) inductor.

A simple approach is proposed for fabrication of percolated perpendicular media (PPM). Nano pore array with pore diameter of 12-15 nm and different pore densities has been prepared by anodizing aluminum on silicon wafers. The pore density increases from 3.2 x [10.sup.10] [cm.sup.-2] to 11.0 x [10.sup.10] [cm.sup.-2] with the decrease in anodizing voltage from 30 to 10 V. Then, Pt (7 nm)/{Co (0.5 nm)/Pt (2) nm}5 multilayers are deposited onto this porous anodized alumina (AAO) by sputtering. The pore size is reduced to 10-12 nm after deposition of magnetic layers. The Co/Pt multilayers on AAO exhibit perpendicular magnetic anisotropy, squarness ratios of unity, and negative nucleation fields. The perpendicular coercivity increases linearly with the increase in pore density due to the pinning effect imposed by the pores, which is consistent with theoretical calculation for PPM. Index Terms--Anodized aluminum oxide (AAO), Co/Pt multilayers, percolated perpendicular media (PPM), pinning sites.

The effectiveness of A1 lop layer and A1 underlayer on the crystallization temperature of hexagonal Barium ferrite (BaM) thin film was studied. All of the BaM films were deposited on Si (111) substrate without any substrate heating. Then, flash annealing was carried out to crystallize the BaM film. A very ultrathin A1 top layer of 5 nm was helpful for improving the crystallographic properties of BaM thin film, but the effect was more intensified when Al was used as an underlayer instead of a lop layer. From the X-ray diffraction (XRD) diagram, the c axis orientation of BaM film with an Al underlayer was confirmed even though the annealing temperature was reduced to 650[degrees]C. The saturation magnetization value also supports the XRD data. From the experimental data, it was found that the Al underlayer can reduce the crystallization temperature of BaM in the range of 600 [degrees]C to 625 [degrees]C by flash annealing for 1 min. The nanocrystalline structure of the Al underlayer promotes the crystallization of BaM very remarkably and hence reduces the crystallization temperature. Index Terms--Al, Ba-ferrite, hexagonal ferrite, perpendicular recording, Si substrate, thin-film media.

[Si.sub.3][N.sub.4], a new substrate as well as thermally oxidized Si[O.sub.2]/Si wafer substrate were used to prepare hexagonal Barium ferrite (BaM) thin films by facing target sputtering system. At substrate temperature (Ts) of 600 [degrees]C, the intensities of BaM (00l) planes in X-ray diffraction diagrams were much stronger in the case of [Si.sub.3] [N.sub.4] substrate than that of Si[O.sub.2]/Si wafer substrate. The value of [DELTA][[theta].sub.50] was found about 2.28[degrees] for 25-nm thickness of BaM deposited on [Si.sub.3] [N.sub.4]. Then, T8 was reduced to 525 [degrees]C. Perpendicular coercivity (H[c.sub.perp]) and squareness ratio ([S.sub.perp]) were higher in the case of [Si.sub.3] [N.sub.4] substrate even at 525 [degrees]C. The maximum value of H[c.sub.perp] = 3.25 kOe and [S.sub.perp] = 0.7 was found for the film of 35 nm. It was found that [Si.sub.3] [N.sub.4] not only reduces the Ts of BaM during in-situ deposition but also increases the perpendicular anisotropy of BaM thin film. Index Terms--Ba-ferrite, hexagonal ferrite, perpendicular-recording, [Si.sub.3] [N.sub.4], thin-film media.

A simple nanofabrication process is introduced to tune the exchange bias in the magnetic nanostructures and the InMn/CoFe films are deposited on the porous alumina oxide (AAO) with different pore different diameters. The results have shown that exchange bias is tuned by the AAO pores.

A simple method is used for fabricating 25 nm magnetic nanodot arrays with perpendicular anisotropy over 10 [cm.sup.2] coverage area. The results have shown that the magnetization reversal of the continuous film is governed by domain-wall motion and the structure is considered as an isolated nanodot array.

A simple method is demonstrated to fabricate 25 nm magnetic nanodot arrays with perpendicular anisotropy over 10 cm2 coverage area. The nanodot arrays are fabricated by depositing Co/Pt multilayers (MLs) onto the SiO2 dot arrays formed on a Si wafer. At first, arrays of the SiO2 dots are fabricated on a Si wafer by anodizing a thin Al film deposited on it. The SiO2 dots are formed at the base of the anodized alumina (AAO) pores due to the selective oxidation of the Si through the AAO pores during over anodization of the Al film. The average diameter, periodicity, and height of the SiO2 dots are about 24, 43, and 17 nm, respectively. Then {Co(0.4 nm)/Pt(0.08 nm)}8 MLs with a 3 nm Pt buffer layer is deposited onto the SiO2 dot arrays by sputtering. The average diameter and periodicity of the Co/Pt nanodot arrays are 25.4 and 43 nm, respectively, with narrow distribution. The nanodot arrays exhibit strong perpendicular anisotropy with a squareness ratio of unity and negative nucleation fields. The coercivity of the nanodot arrays is about one order higher than that of the continuous film, i.e., the same structure deposited on the SiO2 substrate. The magnetization reversal of the continuous film is governed by domain-wall motion, while the magnetization reversal of the nanodot arrays is dominated by the Stoner–Wohlfarth-like rotation. These results indicate that the fabricated structure can be considered as an isolated nanodot array. [ABSTRACT FROM AUTHOR]

The high-frequency characteristics of the RF integrated inductors with antiferromagnetic/ferromagnetic (AF/F) multilayers (MLs) are studied. Each AF layer is 8-nm IrMn and F is Co50Fe50 with a 200-nm splitting into N = 1 to 5 repeats of MLs. This exchange coupled {IrMn/CoFe(d nm)}N MLs are deposited on top of the two-port inductors with five-turn square spiral coils, a dimension of 100 μm × 100 μm and line/space of 5 μm/2 μm. The inductor surface and magnetic layer is separated by 1-μm-thick SiO2. The enhancement of inductance (AL) is 20% compared to an air-core of the same coil size. The resonance peak gradually shifted to a higher frequency with increasing N, and reached at a maximum of 4.3 GHz when N = 5. This is in good agreement with our magnetic data which revealed that the anisotropy field (Hk) and ferromagnetic resonance frequency (fFMR) of {IrMn/CoFe(d nm)}N MLs are increased with increasing N. The quality factor, Q is improved by 6.8% at 1.5 GHz for the {IrMn/CoFe(40 nm)}N=5 integrated inductors compared to air-core inductors. [ABSTRACT FROM AUTHOR]

Si3N4, a new substrate as well as thermally oxidized SiO2/Si wafer substrate were used to prepare hexagonal Barium ferrite (BaM) thin films by facing target sputtering system. At substrate temperature (Ts) of 600 °C, the intensities of BaM (00l) planes in X-ray diffraction diagrams were much stronger in the case of Si3N4 substrate than that of SiO2/Si wafer substrate. The value of Δθ50 was found about 2.28° for 25-nm thickness of BaM deposited on Si3N4. Then, Ts was reduced to 525 °C. Perpendicular coercivity (Hcperp) and squareness ratio (Sperp) were higher in the case of Si3N4 substrate even at 525 °C. The maximum value of Hcperp = 3.25 kOe and Sperp = 0.7 was found for the film of 35 nm. It was found that Si3 N4 not only reduces the Ts of BaM during in-situ deposition but also increases the perpendicular anisotropy of BaM thin film. [ABSTRACT FROM AUTHOR]

Si3N4, a new substrate as well as thermally oxidized SiO2/Si wafer substrate were used to prepare hexagonal Barium ferrite (BaM) thin films by facing target sputtering system. At substrate temperature (Ts) of 600 °C, the intensities of BaM (00l) planes in X-ray diffraction diagrams were much stronger in the case of Si3N4 substrate than that of SiO2/Si wafer substrate. The value of Δθ50 was found about 2.28° for 25-nm thickness of BaM deposited on Si3N4. Then, Ts was reduced to 525 °C. Perpendicular coercivity (Hcperp) and squareness ratio (Sperp) were higher in the case of Si3N4 substrate even at 525 °C. The maximum value of Hcperp = 3.25 kOe and Sperp = 0.7 was found for the film of 35 nm. It was found that Si3 N4 not only reduces the Ts of BaM during in-situ deposition but also increases the perpendicular anisotropy of BaM thin film. [ABSTRACT FROM AUTHOR]