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The 7-hole probe measurement system is mainly used to measure three-dimensional flow fields. During the measurement, the probe head was in direct contact with the measured object, and the head structure had a significant influence on the accuracy of the flow field measurement. The main influencing factors were the hole opening mode, hole position, and hole diameter. For a hemispherical 7-hole probe with perpendicular and forward-facing holes, orthogonal experiments with three levels and three factors (inflow velocity, hole position, and hole diameter) were designed, and additional experiments were conducted on the significant factors. The importance of factors was evaluated based on the correlation between different structural parameters and the pressure coefficient. The experiment was simulated using FLUENT, and the numerical simulation results demonstrated that the square of deviance at the inlet velocity, hole diameter, and hole position was 0.0018, 0.0013, and 0.3611, respectively. The position of the hole has a significant influence on the measurement results, but the influence of the inflow velocity and hole diameter is negligible, and the pressure coefficient is the smallest when the hole is at 45°. For the hemispherical 7-hole probe with forward facing hole, the hole is the best at approximately 45°, and considering the convenience of processing, the diameter of the hole can be selected as the diameter of the 1/10 probe.

Approaches for automatic computing footprint Chippaux-Smirak Index by using Curve Slope Estimation and Perpendicular Line Detection methods are proposed in this paper. First, the k-mean clustering and the Circular Hough Transform approaches are applied to divide the footprint image into left and right sides and then removed the toe prints. Then, the horizontal integral intensity projection method is applied to obtain the position of the anterior and the posterior aspect of the toeless footprints. All boundary points of the footprint are located by the Morphological Gradient method. Subsequently, the slope of a curve at the point of tangency and the straight-lines which plane of the Lateral Calcaneal on the outside of the footprint image are then estimated. Finally, the length of the straight-line at the narrowest point on the foot arch, the length of the straight-line at the widest point at the metatarsals, and the footprint Chippaux-Smirak Index value were calculated by applying the Euclidean method. Footprint arch type are then classified by using the cutoff value of the Chippaux-Smirak Index. In this experiment, the average accuracy for automatic computing Chippaux-Smirak Index values in the footprint image is 90.17% and the accuracy for classification of the footprint arch type is 87.86% in comparison with the manual computation from the expert.

Photonic crystal has been proved to manipulate light effectively and improve the performance of solar cells. In this paper, high-performance GaAs-based solar cells with photonic crystal were fabricated to decrease the dependence on the angle of incident light. Photoluminescence (PL) intensity of solar cells with photonic crystal reduced only 8% when the incident angle changed from 10° to 30°, while the PL intensity of the ordinary solar cells decreased 39% under the same condition. It manifests the photonic crystal can manipulate the incident light in turn reduce the dependence of incident light angle. Besides, the short circuit current of solar cells was increased by 32% after the photonic crystal was added. When the incident angle of light increased to 30° from 0°, the short circuit current of ordinary solar cell decreased 29.5%, while that of solar cell with photonic crystals reduced 12%. Correspondingly, the photoelectric conversion efficiency (PCE) of ordinary solar cells was reduced 31.2%. In contrast, solar cells with photonic crystal decreased only 11.5%. The enhancement factor of the PCE of solar cells with photonic crystal to that of ordinary solar cells increases from 1.26 to 1.6 as the incident angle rises to 30°from 0°. In summary, solar cells with photonic crystal are less sensitive to the incident angle and could absorb more light without angle limits, then increase the PCE. These solar cells with photonic crystals are promising in low-cost and high power conversion efficiency solar cell fields.

External magnetic field resistance under write, read operations for perpendicular STT-MRAM qualified for 260°C solder reflow is comprehensively reported for the first time. We show that the most critical polarization direction is writing from parallel to anti-parallel state with external field opposed to both the final free layer direction and the bottom pinned layer direction. It is also found that free layer failure to switch is the major cause rather than unexpected pinned layer flipping. Furthermore, various key factors including temperature, write condition and MTJ film stack are also studied here. Finally, we demonstrate that a low chip failure rate of 0.001 ppm can be achieved with an ECC scheme for external magnetic fields up to 240 Oe at 85°C.

As the term “3-dimensional technology” is gradually getting known by the public in recent years, more and more 3D products come into our daily life, such as 3D cameras, etc. This paper focuses on the control system design of 3D camera platform on perpendicular bracket. The design is based on single-chip's control to steering engine, which enables the camera to be operated by a remote-controller and has a broad market and great development.

In-plane current-induced strong dampinglike spin-orbit torque (SOT) can enable sub-nanosecond switching of thin-film nanomagnets for nonvolatile magnetic storage [1] . Enormous efforts have been made on developing energy-efficient, high-endurance, integration-friendly spin current generators (SCGs) [2] , [3] that can provide high dampinglike SOT efficiency $\left( {\xi _{DL}^j} \right)$ . This is mainly motivated by the fact that $\xi _{DL}^j$ of a SCG/ferromagnet (FM) heterostructure directly connects to the density of the critical switching current inside the SCG layer ( j c ) and thus the total switching current ( I c , the sum of the currents in the SCG and the FM layers) that will define the energy efficiency $\left( { \propto I_{\text{c}}^2} \right)$ , the scalability (the transistor dimension ∝ I c ), and the endurance (electro-immigration $ \propto I_{\text{c}}^2$ ) of spin-orbit torque magnetic tunnel junctions (SOT-MTJs).

For the first time, 4Gbit density STT-MRAM using perpendicular MTJ in compact cell was successfully demonstrated through the tight distributions for resistance and magnetic properties. This paper includes the results regarding parasitic resistance control process, MTJ process, and MTJ stack engineering. Both of successful 4Gb read and write operations were performed with high TMR, low Ic. This result will brighten the prospect of high-density STT-MRAM.

Spin transfer torque magnetoresistive random access memory (STT-MRAM) is being developed as a candidate for the next generation memories nowadays.

Since the discovery of a theoretical idea of spin-transfer torque (STT) [1], STT-MRAM has attracted a great interest as a candidate of universal memory.

To achieve a misalignment-free wireless power transfer (WPT), an IC for an adaptive magnetic field adder (AMFA), where the magnetic fields from multiple transmitter (TX) coils are adaptively added based on the coupling coefficient (k) between each TX coil and the receiver (RX) coil, is realized for the first time. A 6.78 MHz AMFA IC fabricated in 1.8 V, 180 nm CMOS integrating four power amplifiers (PAs) and shared k sensor increases the perpendicular WPT efficiency from 0.02 % to 48.2 % with the load power of 458 mW.

Spin-Orbit Torque Magnetic Random Access Memory (SOT-MRAM) with perpendicular magnetic anisotropy (PMA) materials have received greater interest because of their advantages such as low magnetization switching current and fast switching time. Recent studies reported spin-orbit torque in NM/FM/MgO structure with PMA using various non-magnetic materials (Ta, W, Pt, etc.) and ferromagnetic materials (CoFeB, Co, etc.) [1]–[3].

Recycling of printed circuit boards (PCBs) is still subject to current research. For identifying valuable materials in electronical components on the PCBs the height profile of PCBs is a important feature. Laser triangulation with a perpendicular laser is a classical approach to generate height profiles. However, in such a setup it is not possible to acquire different modalities such as panorama images and the height profile simultaneously. The solution is to use a setup in which the laser is slanted and the camera is perpendicular to the PCBs. A new triangulation approach employing raycasting and intersecting a laser plane and a ray of sight is needed to retain accuracy of the height profile generation. Evaluation results show that the accuracy of height measurement with an average error of 0.077mm is still sufficient for detecting small surface mounted devices on PCBs with a minimal height of about 0.2 mm.

Carbon overcoats play an important role in the corrosion protection of recording media used in hard disk drive technology. For achieving high areal density, there is a need to reduce the magnetic spacing. Since Carbon overcoat thickness is one of the major contributors to the spacing, it is essential to design suitable overcoats that can protect the media even when they are thin. Filtered cathodic vacuum arc (FCVA) has been studied in the past as potential media overcoat. In order to achieve desired property of FCVA carbon, it is essential to apply a suitable bias voltage, which results in an energetic carbon deposition on the magnetic layer of the recording media [1]. We have recently reported the preliminary results of damage caused on antiferromagnetically coupled (AFC) media layer based on XPS and some magnetic characterization techniques [2]. In this paper, we focus our attention on the implantation effects of energetic carbon on the magnetic and structural properties of recording media of two types; AFC and a single layer, in order to gain more meaningful insight on the implantation and its effect.

Traditional spin transfer torque MRAM (STT-MRAM) uses one transistor and one MTJ (1T-1MTJ) architecture, where the transistor provides bi-polar currents to switch the magnetization of the free layer of the MTJ. Due to the limitation of the maximum current that is available from a typical transistor, for a MTJ device with required thermal stability and data retention at extreme densities, the size of the transistor that is needed to provide a high enough current to switch the magnetization of the free layer of the MTJ may impose an ultimate limitation on the STT-MRAM area data density that can be achieved.

We searched solutions of the Landau-Lifshitz-Gilbert-Slonczewski equation of micromagnetism by using the Simulated Annealing algorithm. The solutions were expressed as a composition of perpendicular harmonic oscillations. For a spin-torque oscillator with perpendicular-to-plane polarizer and in-plane magnetization free layer, both stable states and steady state oscillations of the free layer magnetization were obtained. A linear variation of the frequency oscillation with the current density was obtained. The approach presented is useful in exploring the behaviour of a spin-torque oscillator without imposing initial conditions for the free layer magnetization.

Spin-Transfer-Torque Magnetoresistive Random Access Memory (STT-MRAM) has attracted great attentions as an emerging non-volatile memory. For embedded application, its memory cell i.e., perpendicular magnetic tunnel junction (p-MTJ) needs to withstand the $400 ^{circ}\mathrm {C}$ thermal process which is involved in the semiconductor back-end-of-line (BEOL) process. Although several groups have reported $400 ^{circ}\mathrm {C}$ thermal robustness [1], [2], the key required atomic-level structure for p-MTJs has not yet been clarified. In this work, we have achieved $400 ^{circ}mathrm{Cp} -$MTJ thermal robustness with an untrathin FeTa decoupling layer in the pinned layer, and analysed the atomic-level structure of the film. By comparing the crystal structures of thermally robust and thermally degraded p-MTJs, we have identified that decoupling the body-centered cubic (bcc) CoFeB reference layer and the face-centered cubic (fcc) Co/Pt superlattices is essential in achieving good thermal stability. Firstly, we have confirmed the thermal robustness of a thick p-MTJ against $400 ^{circ}\mathrm {C}$ as reported in Ref. [3]. The p-MTJ structure is Sub/Ta (1.2)/Pt (2.0)/[Co (0.3)/Pt $( 0.5 )] _{6} /$Co (0.5)/ Ru (0.85)/Co (0.5)/Pt (0.5)/[Co (0.3)/Pt $( 0.5 ) ] _{4} /$Ta (0.3)/Co 20 Fe $_{60} \mathrm {B}_{20}(1.2) /$MgO(1.0)/Co 20 Fe $_{60} \mathrm {B}_{20}(1.2) /$Mo(2.0)/Cap [thickness in nm]. However, for a thinner pinned layer p-MTJ by reducing the Co/Pt repetitions from 4 to 2 labelled as the conventional p-MTJ in Fig. 1(a), thermal stability degradation was observed from the major $M-H$ loops [Fig. 1(b)]. Since the free layer exhibited sufficient thermal stability as shown in the inset of the figure, we speculated that thermal degradation could be initiated from the crystal interference in a thin region of Ta insertion layer where the bcc and fcc crystals meet each other. In order to solve this issue, we proposed a FeTa insertion layer to replace the Ta layer. The improved p-MTJ structure is shown in Fig. 1(a). FeTa was selected due to its amorphous structure as deposited. Under $400 ^{circ}\mathrm {C}$ thermal annealing, it could nucleate and grow in an epitaxial manner along both bcc and fcc crystal boundaries of the neighbouring layers. This unique crystallization behaviour enables FeTa to act as a buffer to effectively decouple the bcc and fcc crystal structures. Regarding the magnetic function, the required ferromagnetic exchange coupling between the CoFeB reference layer and the Co/Pt superlattices was obtained thanks to the intrinsic magnetic property of FeTa alloy. As a result, the thermal robustness against $400 ^{circ}\mathrm {C}$ has been successfully achieved for the improved p-MTJ. Fig. 1(c) shows the decent major and minor $M-H$ loops with little thermal degradation for the improved p-MTJ. To clarify the mechanism for achieving thermal robustness of the improved p-MTJ, we adopted the spherical aberration corrected Scanning Transmission Electron Microscope (Cs-corrected STEM) to visualize the atomic-scale structural difference at the Ta and FeTa interfaces (Fig. 2). Images show that a flat interface is present with the improved FeTa sample, and its CoFeB reference layer is more crystalline structured. In contrast, the conventional Ta sample shows a rougher crystal interface and the CoFeB reference layer tends to be amorphous. The structural difference suggests that the FeTa layer is more effective in decoupling the bcc and fcc crystal structures. This result could also account for the observation by another group that a thicker CoFeB reference layer resulted in thermal stability degradation [2]. Theoretically, a thicker film layer leads to a better thermal tolerance owing to its more robust crystal structure. However, when comes to a complex p-MTJ system consisting of both bcc and fcc lattices in an ultrathin region, a thicker CoFeB layer enhances the structural integrity of bcc lattice against the fcc Co/Pt superlattices. This subtle thickness change may break the thermodynamic equilibrium status between these two lattices during $400 ^{circ}\mathrm {C}$ thermal process, thus causing the degradation of perpendicular magnetic anisotropy originated from the Co/Pt superlattices. This also explained the slightly thermal degradation of the improved p-MTJ when thickening the CoFeB reference layer from 0.8 nm to 1.2 nm even though the FeTa insertion layer can realize more effective crystal decoupling between the bcc CoFeB and fcc Co/Pt superlattices. In summary, maintaining the crystal integrity of both the CoFeB bcc and Co/Pt fcc crystal structures and well control of their interface are essential in achieving good p-MTJ thermal tolerance for embedded STT-MRAM application.

In this paper a new method to detect the center of a circle is proposed. This method uses pairs of perpendicular bisectors of each two no-repeat intersecting chords to calculate the intersection which is the center of the circle. It can overcome the drawbacks of deviation caused by edge points nonuniformly distributed by centroid method, and drawbacks of highly computation time and a large amount of storage which is brought by Hough Transform, and drawbacks of much disturbance by random noises brought by least square method. Experimental results show that the perpendicular bisector method can eliminate the disturbance of random noises, and can obtain exact circle center rapidly. It can reach an accuracy of less than one pixel for circle center detection.

Fabrication of both linear and perpendicular junctions of one-dimensional molecular assembly (molecular line) on Si(100)-(2 × 1)-H surface and it's fine structure have been investigated using scanning tunneling microscope (STM) at 300 K. The end-molecule of a styrene line appears brighter than other molecules of the line in STM image after forming a perpendicularly connected allylmercaptan line. The observed changes in image height of the end-molecule after junction formation is ascribed to the shifting of frontier energy states of the junction molecule by interaction with nearby allylmercaptan molecules. Unlike perpendicular junction, the molecule at linear junction consisting of benzophenone and 4,4'-dichlorobenzophenone lines do not show significant change compared to the bulk molecules. The alignments of the styrene molecules in a doubled molecular line are discussed.

Since the initial prediction and experimental demonstration of magnetization reversal by spin transfer torque (STT), there has been continuous progress toward the development of nonvolatile magnetic random access memory based on STT switching (STT-RAM) in nanoscale magnetic tunnel junctions (MTJs). In the most common STT-RAM configuration shown in Fig. 1(a), the magnetic moments of the free layer and the pinned polarizing layer of an MTJ lie collinear to one another in the plane of the junction. In this configuration (in-plane STT-RAM or IST-RAM), STT is small during the initial stages of the free layer's magnetic moment reversal, resulting in a relatively long nanosecond-scale switching time. Switching can be greatly accelerated in an alternative STT-RAM configuration, in which a second polarizer with magnetic moment perpendicular to the MTJ plane is added to the magnetic multilayer (orthogonal STT-RAM or OST-RAM). The initial STT from the perpendicular polarizer is large and has been predicted to induce ultrafast precessional switching of the free layer's magnetization on a time scale of 100 ps. The differences in the reversal modes expected for the IST-RAM and OST-RAM devices are illustrated in Figs. 1(c) and 1(d), wherein magnetization switching trajectories are shown for the two types of memory.

This work reports sub-nanosecond precessional spin-transfer switching in elliptical magnetic tunnel junction nanopillars. This result is obtained in samples integrating a perpendicular polarizer and a tunnel junction with in-plane magnetized electrodes. We have performed statistics on time-resolved electrical measurements showing oscillations of the switching probability as a function of write voltage pulse width. This behavior is characteristic of the free layer precessional motion induced by the perpendicular polarizer. Ultrafast STT switching in less than 300ps could be achieved in these structures with corresponding write energy less than 100fJ.

The development of hybrid Magnetic-CMOS circuits such as MRAM (Magnetic RAM) and Magnetic logic circuit requires efficient simulation models to describe the magnetic devices electrical behavior. A compact-model of Magnetic Tunnel Junctions (MTJ) is presented in this paper. This device is the most commonly used magnetic components in CMOS circuits. This model is based on Spin-Transfer Torque (STT) with a perpendicular polarizer writing approach. The current-induced magnetic switching and excitations was studied in structures comprising a perpendicularly magnetized polarizing layer (PL), an in-plane magnetized free layer (FL), and an in-plane magnetized analyzing layer (AL).

In this study, the spatial distribution of MSF in CoCrPt-Si02 granular perpendicular recording medium and CoCrPt patterned medium are reported. MFM images were observed with a SPA300HV scanning probe microscope coupled to an electromagnet producing a controllable perpendicular magnetic field of up to 10 kOe in a vacuum. The diameter of the cutting edge of the probe tip was less than 30 nm. Measurement conditions, such as the vibration amplitude of the tip (15 nm for morphology scanning and 3 nm for phase measurement), tip-to-sample distance (~8 nm), and Q factor (~3500) of the cantilever, were carefully selected and controlled so that a resolution of about 15-20 nm could be expected. tial fluctuations of the magnetic switching field. MSF-map

The classical amplitude spectrum and full amplitude spectrum have obvious defects in analyzing the rotor's two perpendicular directional vibration displacement signals at a section. Classical amplitude spectrum is influenced by the installation angle of the sensors, and both classical amplitude spectrum and full amplitude spectrum can't reflect the actual shaft vibration amplitude at every frequency. To solve these problems, this paper puts forward a method of synthetic amplitude spectrum (SAS). The paper discusses the principle of SAS, provides its specific doing steps. The experiments show that SAS and its extension methods are no longer influenced by the installation angle of two sensors, but guaranteeing that the solved amplitude of the spectrum can reflect the actual shaft vibration amplitude at its corresponding frequency.

Position error signal (PES) plays a crucial role in hard disk drives by providing the position information of the read head to the servo controller. In this paper, we examine the performance of PES from different servo patterns for high density perpendicular recording system using microtrack simulation. The results reveal certain impacts of perpendicular recording on servo pattern design and provide references on PES signal generation and decoding method design for future hard disk drives (HDD) based on perpendicular recording technology.

Perpendicular magnetic recording (PMR) has been recognized for many years as having the potential to extend recording densities beyond the capabilities of longitudinal recording. This paper discusses the challenges in designing perpendicular thin-film recording media materials.

In this study, Nd2Fe14B thin films with perpendicular anisotropy at the thickness as thin as 5 nm have been successfully prepared. The suitability of the films as perpendicular magnetic recording media has been discussed. The films were characterized by X-ray diffractometry (XRD), vibrating sample magnetometer (VSM) with maximum applied field 24 kOe, and scanning electron microscopy (SEM). The chemical stability of the films was evaluated by measuring the change of magnetic properties at ambient atmosphere for different capping layer thickness.

We present experimental results for a series of perpendicular recording media samples, using magnetometry methods adopted for the perpendicular geometry. The inadequacy of characterization using only hysteresis loops is demonstrated, as well as the influence of a demagnetization field and its importance for the interpretation of the results. By using the more involved and time-consuming measurements described in this work, some of the relevant materials properties can be determined and serve as inputs for advanced micromagnetic recording models.

Recently there is an arising interest in perpendicular recording due to its intrinsic advantages for ultra-high recording density. At present, one key issue for increasing the recording density is how to minimize the system noise, which is dominated by the media transition noise and directly related to the switching field distribution (SFD) of the magnetic media. SFD is the dispersion of the lowest magnetic field required to switch the magnetization directions of grains. In granular perpendicular media, the magnetocrystalline anisotropy easy axes of the grains in the medium are virtually in the direction normal to the film plane. In recent head design, a shielded pole head/SUL, which is the combination of a trailing shield with a MP head, is proposed to provide high field gradient in recording. However, the trailing shield also introduces a, large horizontal field component on the media plane and consequently provides a larger switching field angle compared with the MP head. By optimizing the SP/SUL geometry we can obtain the desired switching field angle on the media plane. A 2-D micromagnetic model, which :is based upon the Landau-Lifshits-Gilbert equation, was used to simulate the dynamic recording process and evaluate the designed recording system.

In this paper, the evaluation results of the performance of discrete track perpendicular media is described. Discrete track patterns for data area and servo patterns such as address marks and burst patterns for each sector are formed by nano-imprint lithography and the dry etching process. Comparison of the error rate profile in both the discrete track media and conventional media is shown. Write and read operations are conducted by a perpendicular magnetic head which has MWW of 195 nm and MRW of 100 nm. In the conventional media, the error rate of the center-track is degraded due to the side-writing and cross talk. On the other hand, in the discrete track media, the error rate is kept unchangeable. This is because the grooves between the tracks prevent the side-writing and cross talk. In addition, higher SNR is observed at the narrower track pitch in the discrete track media.

We report on a novel spin torque select MRAM with perpendicular anisotropy (P-ST-MRAM). The P-ST concept offers superior scalability performance at the 28 nm technology node compared to the conventional in-plane spin torque MRAM (I-ST-MRAM). The critical programming currents (~ 30 muA) are low, allowing a cell layout as small as 6 F2. In addition, data retention is significantly better for P-ST enabling a non-volatile, high density product for the 28 nm node. Estimations on write performance promise high write endurance and high write speed. Circuit simulations with improved read circuit demonstrate array read access time ~ 30 ns at sensing currents ~ 10 muA.

A beam-switching antenna which is composed of several independent antennas with different beam directions is one of the realistic solutions of an electronic beam-scanning antenna, because it does not need any special feeding circuits. Excitation phases of radiating elements in traveling wave antennas are controlled by changing the connection point along the feeding line. As the radiating elements are connected on the both sides of the feeding line, the effective element spacing in the perpendicular direction of the feeding line of the comb-line antenna can be almost a half of the spacing of the feeding lines. The amplitude distribution is also designed for low-sidelobe characteristic. In this paper, a five-beam switching antenna composed of five independent microstrip comb-line antennas with five different beams is proposed. The performance of the proposed antenna is demonstrated by simulation and measurement in this work.

CoCrPt-SiO2-based perpendicular recording medium with a crystalline soft underlayer (c-SUL). Low Deltathetas50 of about 3 deg with a thin intermediate layer of 5 nm has been made in this media. In this paper, we report the orientation improvement, noise reduction of c-SUL and recording performance of the media. The magnetic properties and microstructure were characterized by magneto-optic Kerr effect (MOKE) magnetometer, X-ray diffraction (XRD), transmission microscopy (TEM), and optical surface analyzer (OSA). Recording performance was measured by a Guzik spinstand stand tester with a ring-head writer and a MR reader.

This article reports the effect of varying the damping in different individual sections of the perpendicular recording head (like the yoke, pole and soft underlayer (SUL) regions) affects the head switching speed. Two head designs were used: the shielded head and monopole head design. The head model used in this paper divided the head into five regions: a) soft underlayer, b) tip, c) confluence, d) yoke, and e) shield. Results show that higher damping generally results in higher field amplitudes because the head field rise time is improved.

Due to the period 3-D structure, photonic crystals would form photonic bandgap. They are more important and widely used in optical communication, energy and display regime. The relationship between distances of circular photonic crystals and wavelength in perpendicular corner propagation is investigated in this study. There are six types of propagation found in the results. With the maximum propagation efficiency, the relationship between distances of circular photonic crystals and wavelength is the curve of decay ripple wave like. And it is found under different distances of photonic crystals, there are three types between the propagation efficiency and wavelength.

Intermediate layers for perpendicular magnetic recording media have been studied for controlling storage layers with fine grains. The magnetic properties of the media was investigated for understanding the effect of the intermediate layer. H/sub c/spl perp// for the medium with the Pt/C intermediate layer showed a little bit large value compared with that with the Pt/Ti one. TEM images of the media were investigated. We show that platinum and carbon layers are suitable intermediate layers for a very fine Co-Cr-Pt-Nb storage layer in double layered perpendicular magnetic recording media.

There have been intensive research activities on perpendicular magnetic recording media using CoCrPt-SiO/sub 2/ material as the recording layer. To obtain a relatively high coercivity and good crystallography relatively thick Ru thickness is necessary. In this paper, we studied the effect if NiCr and NiFeCr seedlayer on the magnetic properties and crystallography of CoCrPt-SiO/sub 2/ PMR media using vibrating sample magnetometer and X-ray diffractometry (XRD). The PMR media were deposited by sputtering on a glass substrate.

Current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) pillars with epitaxially grown FePt/Au layers were fabricated by magnetron sputtering. Structure, magnetic properties and transport properties have been investigated using X-ray diffraction, superconducting quantum interference device magnetometer and conventional dc four-probe method respectively.

A magnetometry method was developed for the experimental characterization of intrinsic switching field distributions in perpendicular media. The applied field difference /spl Delta/H between the various recoil loops and the major loop was measured for identical distance M-values away from saturation, i.e. the same average demagnetizing fields. Also, a more refined measurement of the entire switching field distribution D(H/sub S/) was gained by analyzing the complete /spl Delta/H(M,/spl Delta/M)-data set from multiple recoil loops. Using micromagnetic modeling, the reliability and precision of the described /spl Delta/H(M,/spl Delta/M) method was studied.

CoPtCr-SiO/sub 2/ perpendicular recording media with varying levels of SiO/sub 2/ were examined by two different methods to determine the activation volume. The first is based on the sweep-rate dependence of the remanence coercivity using Sharrock's equation. The second is based on the measurement of the fluctuation field from time-dependence data, determined using a magneto-optical Kerr effect (MOKE) magnetometer. The values of V/sub act/ measured at the coercivity for both methods are almost the same, with the fluctuation field and activation volumes increasing with the SiO/sub 2/ content. The difference between V/sub act/ and the grain volume measured directly from bright-field TEM images decreases as the SiO/sub 2/ content increases due to the reduction of intergranular exchange coupling. The experimental results indicate that values of V/sub act/ obtained from single- and double-layered media are consistent. It was also found that the coercivity and normalized hysteresis loop slope at coercivity varied with SiO/sub 2/ content, with the coercivity peaking at 8 at%SiO/sub 2/ (nearly 26 vol%SiO/sub 2/).

A novel electroless CoNiFe soft magnetic thin film is grown on a single-crystalline Si wafer disk substrate by electrochemical deposition. The microstructure, chemical composition, magnetization, and magnetic domain structure of the films are evaluated with the use of cross-sectional transmission electron microscopy, energy-dispersive X-ray analysis, vibrating sample magnetometer and surface magneto-optical Kerr effect analysis. Results show a highly fcc oriented nanocrystalline structure which exhibits no distinct magnetic domain walls with a large in-plane unidirectional magnetic anisotropy and a low magnetic coercivity.

This paper investigates the effect of varying the exchange-break-layer thicknesses (leading to a change in intergranular exchange) on spectral rolloff and the transition parameter (a-parameter). The rolloff curves are obtained by measuring the amplitude of the fundamental harmonic peak at each written density. A systematic increase of the low frequency amplitude is observed as the EBL thickness decrease.

Two types of media with a high-Bs Fe-Co soft underlayer (SUL) were prepared to reduce the film thicknesses of the Ru intermediate layer and the SUL. The crystal orientation of the media was greatly changed by using a thin Ta underlayer. The magnetic properties of the SULs were similar, independent of the existence of the Ta underlayer. However, the media with high orientation have large Hc and squareness ratio. The Ru layer thickness for obtaining the maximum Hc and squareness ratio is 5-7 nm. This seems to be due to the imperfection of Ru orientation. From the read-write properties, the minimum of the Ru layer thickness is 7 nm. However, from vibrating-sample magnetometer measurements, the magnetic interaction between the recording layer and the Fe-Co SUL is broken by using an Ru layer of 1-3 nm. The intermediate layer thickness could be reduced down to about 1 nm if the orientation is improved

Summary form only given. The width of the media switching field distribution (SFD) is a crucial performance indicator for both longitudinal and perpendicular recording. A broad SFD impacts the SNR and resolution of written transitions. It also indicates the presence of low coercivity grains, which determine the archival lifetime of stored information.

Summary form only given. Patterning magnetic media with pre-defined, single-domain magnetic bits is one possible candidate for extending magnetic storage densities beyond the limit set by thermal decay for continuous media. In order to study the writing and read-back characteristics of high density patterned media, prototype nanometer-scale magnetic structures were made by patterning Co/sub 70/Cr/sub 18/Pt/sub 12/ perpendicular medium using a focused ion beam (FIB) of Ga/sup +/. The islands have lateral size of 80 nm and have a 103 nm along track period. For comparison, we have also used the FIB to prepare isolated narrow strips of continuous media. The recording properties of the patterned and unpatterned media were evaluated using a static write/read tester.

A novel transition from coaxial cable to microstrip is presented in which the coax connector is perpendicular to the substrate of the printed circuit. Such a right-angle transition has practical advantages over more common end-launch geometries in some situations. The design is compact, easy to fabricate, and provides repeatable performance of better than 14 dB return loss and 0.4 dB insertion loss from DC to 40 GHz.

Summary form only given. Magnetization reversal of various kinds of perpendicular recording media was characterized using a pulse magnetometer (T. Shimatsu et al, Digests of PMRC 2000, p. 141, 2000), and discussed relating to media noise performance. Co(B)/Pd superlattice media, CoTb(Pr)/CoCr(Ta,Pt) composite media (T. Shimatsu et al, Digests of MMM Conf., FB-06, 2001; H. Uwazumi, ibid., FB-05, 2001) and CoCr(Ta, Pt, B) media were subjected to the study.

Magnetic tunnel junctions (MTJs) have become a basic building block for various types of spintronics devices, such as magnetic random access memory (MRAM) cells, magnetic field sensors and microwave generators or detectors.

Recently, Spin-Orbit torque (SOT) arising from the ferromagnetic heterostructures consisting of an ultra-thin ferromagnet (FM) sandwiched between a heavy metal (HM) and an Oxide layer has attracted extensive attention in the low power magnetic memory and logic devices.