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In this work, a stable de-aggregated solvent-swollen organic modified clay, ALA–MMT, suspension is prepared by an efficient solvent swelling process using a home-made shaking mixer. It is found that the estimated average size of the as-prepared organoclay particles in the suspension is reduced to about 155 nm, which has not been reported before. The X-ray diffraction (XRD) patterns confirm that the d -spacing of the silicate layers of the solvent-swollen ALA–MMT expands from 1.4 nm to about 2.1 nm. The de-aggregated solvent-swollen ALA–MMT suspension is then used with polyurethane (PU) to prepare a series of highly exfoliated and high-organoclay-loading nanocomposites, PU/ALA–MMT. Both the XRD patterns and the TEM photographs of the as-prepared PU/ALA–MMT nanocomposites indicate that the organoclay is uniformly dispersed in the PU matrix with a highly exfoliated morphology structure of up to 7 wt% loading. Meanwhile, the TEM photographs give the first report for PU/clay nanocomposites which are almost completely exfoliated, and ∼1-nm thin silicate nanolayers are homogeneously dispersed in the polymer matrix with a high aspect ratio of 30–100. The thermal, mechanical, and anti-corrosion properties are all tremendously enhanced for the as-prepared nanocomposites. The results obtained for the PU nanocomposite with 7 wt% ALA–MMT loading (PUC7) reveal a 19 °C increment in T g , a 48 °C increment in T 5% , a 248% increase in the tensile strength, and a 123% increase in the elongation. The stainless steel disk (SSD) coated with PUC7 shows the lowest corrosion rate of 2.01 × 10 −6 mm/year, which is 469% lower than that of the SSD coated with pure PU. The reinforcements are much greater than the previously reported PU/clay nanocomposites with comparable clay loadings ascribed to the exceptional homogeneity of as-prepared nanocomposites, which are accredited largely to the stable de-aggregated solvent-swollen organoclay suspension generated by the efficient solvent swelling process.

It was presented the in situ observation of growth behavior and morphology of delta-ferrite as a function of solidification rate in an AISI304 stainless steel. The specimens have been solidified and observed using confocal scanning laser microscopy (CSLM). The δ-phase always appears like cells on the sample surface when critical supercooling occurs, during which the L→δ transformation starts. The solid-liquid (S-L) interface is found to be finger shaped and has no faceted shape. γ phase appears among δ grains due to partitioning of Ni into the melt during solidification, when solidification rate is higher. The mergence of observed δ cells is possible for the steel sample cooled at 7.5°C/min. The formation of dendrites can be observed on the free surface of the steel sample cooled at 150°C/min. The size of solidified delta grains decreases from 120 to 20–80μm, and the volume fraction of solidified austenite increases with increase in solidification rate from 7.5 to 150°C/min. The relation between the tip radius of δ cell and its growth rate is deduced, and the results agree with the experimental values.

The magnetization switching behavior of permalloy ring elements as a function of ring diameter and film thickness by magnetoresistance measurement is presented. The permalloy ring elements, with diameters of 2–5 μm and a thickness of 14–66 nm, were fabricated by electron beam lithography through a lift-off process. The switching field for the transition from the vortex state to the onion state increases with decreasing size. Furthermore, the switching field increases with increasing thickness up to a critical value of about 53–65 nm, over which the switching field tends to decrease with increasing thickness.

Perpendicular magnetic anisotropy and magnetic domain structure were studied in epitaxial (Co(t C0 )/Pt(10 As )) 30 (t C0 "2, 2.5, 3, 4, 5 and 10 As ) multilayers prepared on Al 2 O 3 (1 1 -2 0) substrate via Mo or Pt seed layer. The best perpendicular magnetic e!ect occurred for t C0 & 3A s. At remnant state the domain size tends to increase as t C0 decreases, and the domain structure depends strongly on the seed layer. For (Co(3 As )/Pt(10 As )) 30 multilayers grown on gold grid made hole arrays, the polar coercivity inside the holes is di!erent from those on the gold land and unpatterned area. ( 2000 Elsevier Science B.V. All rights reserved.

We have shown in previous papers that the magnetic domains could be pinned inside the artificially patterned hole arrays under suitable geometry aspect ratio. Nevertheless, we have found that if we reverse the magnetization directions through domain wall motion, the confined domains expand from smaller territory into larger territory for some samples. In addition, the pinned domains maintained the same moment's orientation after the domain expansion. The possible reason for the pinned domains to retain the same moment's orientation maybe those pinning holes that act as high anisotropy defects. Thus, domain wall motion was around the high anisotropy sites and only peeled away the domain in the land area while the enclosed domain of the hole area maintained the same orientation. Moreover, the feasible reason for the expansion domains is the coercive force, which is perpendicular to the side-walls and pinning the domains inside the holes, are relaxed and thus causing the domains growth. This phenomenon is called the relaxation of pinning domains.

A method for pinning magnetic domains with prescribed shapes has been developed for the magneto-optical thin "lm material Dy x (FeCo) 1~x . The pinning array of holes on the substrate was fabricated using electron beam lithography. The thin "lm of Dy x (FeCo) 1~x sandwiched between SiN layers was deposited onto a patterned polymethyl methacrylate layer. The pinned domains acquire the shape of the holes, while the sharpness of their boundaries depends on the size of the holes. The stability of the pinned domains is a!ected by the sample’s magnetization. In our experiments, the minimum stable domain size pinned within the hole array was found to be around 50 nm in diameter. ( 1999 Elsevier Science B.V. All rights reserved.

A novel method for pinning magnetic domains on pre-formatted pinning sites has been developed for perpendicular magnetic anisotropy magneto-optical (MO) thin film media. The pinning sites were artificial lattices made by patterning a layer of gold grid on the substrate using electron beam lithography. Compared with the work proposed using photo- lithography, our method showed the ability of making smaller pinning domains. Moreover, compared with our previous work using the same electron beam lithography method and creating hole arrays on polymethyl methacrylate, this new method could stand higher film deposition temperatures and avoid the MO films rapid deterioration on a PMMA substrate. In order to investigate the domain pinning behavior we did several different procedures and observed their corresponding domain pinning layouts. Magnetic domains were found to be pinned inside the lattice and resembled the geometric shapes of the lattice. The pinned domains acquired the shape of the lattice. In this article, the star-shaped type of geometry of grid arrays is presented.

This letter presents the comparison of three novel structure supports for on-chip complementary metal-oxide-semiconductor (CMOS)-based micromachined inductors by using a proposed two-step maskless post-CMOS process. A 3-D electromagnetic inductor simulation model is established and calibrated with inductor fabrication. The proposed inductors are applied in the matching network of the double-balanced Gilbert mixer to improve the performance and the mechanical stability. The mixers, with and without micromachined process inductors, are fabricated in a 0.5-mum CMOS process and compared in this letter. The measurement results show a 28.12% increase in conversion gain, a 31.7% improvement in third intercept point, and a 44% reduction in the noise figure.

The coercivity of patterned magnetooptical (MO) thin film media is quite different from that of nonpatterned samples. During the demagnetization process, we observed the sample's magnetic domain motion and structures. It was quite obvious that the coercivity values in the hole regions are unlike those on the land regions for patterned magnetic materials. Nevertheless, it was not possible to compute coercivity of holes and land regions directly. In this study, we measured of microhysteresis curves at a patterned position while mapping coercivity distribution using a Kerr microscope. The submicrometer images of the remanent state of domain reversal patterns were observed using a magnetic force microscope.

We use the micromagnetic simulation to study the reversible and irreversible magnetization processes of the single-domain elliptical permalloy particles. The magnetization curve of the reversible process, which has no hysteresis, obtained by applying the field along the hard axis of the elliptical particle is almost linear, as is the case in the single-domain ellipsoidal particle. On the other hand, due to the occurrence of the nonuniform reversal, the switching field of the irreversible process, which has hysteresis, is reduced significantly compared to that predicted by the Stoner-Wohlfarth model. The nucleation fields of elliptical particles are calculated as a function of ellipse's aspect ratio, and the function reveals a step-like behavior.

We report that electrode engineering, particularly tailoring the metal work function, measurement configuration and geometric shape, has significant effects on the bipolar resistive switching (RS) in lateral memory devices based on self-doped SrTiO3 (STO) single crystals. Metals with different work functions (Ti and Pt) and their combinations are used to control the junction transport (either ohmic or Schottky-like). We find that the electric bias is effective in manipulating the concentration of oxygen vacancies at the metal/STO interface, influencing the RS characteristics. Furthermore, we show that the geometric shapes of electrodes (e.g., rectangular, circular, or triangular) affect the electric field distribution at the metal/oxide interface, thus plays an important role in RS. These systematic results suggest that electrode engineering should be deemed as a powerful approach toward controlling and improving the characteristics of RS memories. Published version

The spatial variation of coercivity on patterned magneto-optical (MO) materials has been studied with a Kerr microscope. Our results show that the coercivity values on arrays made by holes are larger than those observed on the land regions. In contrast with nonpatterned MO media, which present a sharp Gaussian-like distribution, the coercivity distribution in the patterned material is much wider and shows an exponential-type distribution. This article maps the spatial variation of the coercivity on patterned magnetic materials with a spatial resolution of 0.1×0.1 μm2.

Summary form only given. Recently, nanostructured rings have attracted much attention in the application of MRAM design because the shape anisotropy makes it easier to generate a closure flux loop spin configuration, which avoids the field leakage and therefore enhances the data storage density. A Permalloy ring with the size of 187.5 nm outer diameter, 112.5 nm inner diameter, and 30nm thickness has been studied by means of micromagnetic simulation. The authors show the hysteresis loop of the ring from our simulation result, with schematic pictures used to represent the stable states I, II, and III of the plateaus.

Microstructured rare-earth–transition-metal DyFeCo films have been investigated using magnetoresistance and extraordinary Hall-effect measurements. The Hall loops reveal variation of coercive fields depending on the linewidth and the composition of the films. The magnetoresistance curves, with changes up to as high as 1.3%, show positive/negative magnetoresistance peaks centered on the coercive fields depending on the linewidth of the films only. The variation of the coercivity can be attributed to the magnetic moment canting between the Dy and FeCo subcomponents and the existence of the diverged magnetization on the edges, and the anomalous magnetoresistance peaks observed are discussed with the existing theories.

Pinning magnetic domains with defined shapes have been made for magneto-optical thin film material. The pinning array of holes on the substrate was fabricated using electron beam lithography. The domain pinning behaviors were studied by applying an external magnetic field perpendicular to the film plane and imaged by atomic force microscopy in their remanent state. Magnetic domains were found to be pinned inside the hole arrays and reproduced the shapes of the holes. The coercivity in the patterned region is larger than in the nonpatterned region. Moreover, the coercivity inside the hole sites is larger than the land sites.

A novel method for pinning the magnetic domain in artificially pinning hole has been developed for magneto-optical (MO) thin film material Dy/sub x/(FeCo)/sub 1-x/. The artificially pinning holes were fabricated using electron-beam lithography. Hole arrays with square, star, and circle shapes had been made in this study. However, the nanometer scale magnetic domains could be formed inside the hole arrays if the pinning hole geometry was not well defined, and the pinning domain may induce media noise.

The effect of process parameters on the performance of silicon nano-sized etching in an Inductive-Coupled-Plasma Reactive-Ion-Etching (ICP-RIE) system is studied by the Taguchi experimental method. The Standard L9 orthogonal array is considered to evaluate the parameter effect and to obtain the optimum conditions. A total of 9 parameter settings are conducted to investigate the four parameters with three levels for each. The four parameters include the substrate temperature, bias power, gas cycle time and C 4 F 8 gas flow rate. The source power and the SF 6 gas flow rate are respectively fixed to a value of 500 W and 120 sccm. The etching bottom roughness and the etching rate are the quality characteristics to evaluate the parameter effect. The results show that both the C 4 F 8 flow rate and the bias power have the significant influence on the bottom roughness, while both the cycle time and the bias power play an important role on etching rate. And, the optimum conditions are obtained, of which the predicted quality has been confirmed by verification experiment.

In this paper, a novel silicon micromachining using CO2 laser has been demonstrated for the first time. The wavelength of CO2 laser is 10.64 mum and not absorbed by silicon material. So, it cannot do any micromachining for pure silicon. However, as we put a silicon on the top of a glass material, CO2 laser can etch the silicon, even etch through the wafer to be a hole structure. For example, a silicon hole of 525 mum deep can be obtained by CO2 laser machining circular shape for 80 passes at power of 24 W, spot size of 76 mum and scanning speed of 6 mm/sec. In comparison with conventional laser micromachining of silicon, shorter wavelength lasers e.g. Nd:YAG laser with wavelength of 1.06 mum and excimer laser of 248 or 193 nm are used due to the good adsorption of silicon. But the cost of shorter wavelength laser is much higher than CO 2 laser. In comparison with conventional silicon micromachining by dry plasma etching, wet KOH/TMAH etching or wire electrodischarge grinding (WEDG), CO2 laser micromachining is much easier, cheaper and has faster etching rate than plasma etching, and more flexible to make different geometry than wet etching and WEDG. This CO2 laser micromachined silicon technology will be a promising one for the application of microfabrication and MEMS

Permalloy networks have been fabricated using standard electron beam lithography through lift-off technique. Magnetic configurations of the thin film samples are then studied using magnetic force microscopy. The net magnetic poles combining uniform magnetizations from joint arms may lead to various domain configurations in each junction, hence multiple storage states are created in each physical junction.

Summary form only given. The advances in nanolithography and new techniques in probing magnetic domain structures such as magnetic force microscopy (MFM) have given scientists an unprecedented way towards the understanding of micromagnetism. We present results of magnetic domain configurations probed at remanent states as well as under external magnetic fields in microstructured Permalloy thin films. Special interest is focused on the formation and evolution of vortex states in elliptical elements. Various ellipses were delineated using standard electron beam lithography, followed by a thermal evaporation of permalloy in the absence of an external magnetic field. The patterned films were then transferred onto a SiN-coated Si-substrate through a lift-off process in acetone. A magnetic force microscope equipped with an external electromagnet was used to investigate the magnetization configurations.

Summary form only given. Our previous studies indicated that the coercivity of patterned magneto-optical (MO) thin film media is quite different from the non-patterned samples. Especially, the coercivity of the hole area is quite different from the land area. In order to understand the quantitative difference of the coercivity between the hole and land regions, we have used a Kerr microscope to acquire the variation feature of the coercivity over the patterned and non-patterned MO media surface.

Artificial pinning sites have been fabricated for the magnetic domain pinning in perpendicular anisotropy magneto-optical (MO) thin film media. The pinning sites were radial hole array made by patterning a layer of radial gold grid on the silicon nitride (SiN) coated silicon (Si) substrate using a standard electron beam lithography. Various magnetization and demagnetization procedures were performed to investigate the magnetic domain pinning behavior. A polar Kerr microscope was used in situ to monitor the magnetic wall motion and a magnetic force microscope was employed to scan the magnetic domain structures. Magnetic domains were found to be pinned inside the hole array and resembled to the geometric shape of the holes. The coercivity in the patterned MO layer is much higher than in the unpatterned MO layer. Moreover, the coercivity in the larger pinning sites area is higher than in the smaller pinning sites area.

A method for pinning magnetic domains with prescribed shapes has been developed for the magneto-optical (MO) thin film material Dyx(FeCo)1-x. The pinning array of holes on the substrate was fabricated using electron beam lithography. The thin film of Dyx(FeCo)1-x sandwiched between SiN layers was deposited onto a patterned polymethyl methacrylate (PMMA) layer. The pinned domains acquire the shape of the holes, while the sharpness of their boundaries depends on the size of the holes. The stability of the pinned domains is affected by the sample’s magnetization. In our experiments, the minimum stable domain size pinned within the hole array was found to be around 30 nm in diameter.