bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Nb concentration on the microstructure of Al and the magnetoresistive properties of the magnetic tunnel junction with a Nb‐doped Al‐oxide barrier
Authors: Park Sung‐Min , Chung Ha‐Chang , Lee Seong‐Rae 
Published: December 2007

AbstractWe have investigated the composition dependence of magnetic tunnel junctions (MTJs) with Nb‐alloyed Al‐oxide (NbAlOx) and analyzed the microstructure changes and electrical property of Nb alloyed Al‐oxide layer. After annealing, tunnel magnetoresistance (TMR) ratio of MTJ with Nb‐alloyed Al‐oxide barrier increased up to 38.5% at 9.26 at.% Nb. As the Nb concentration increases, the grain size decreases and the microstructure becomes a dense, fine equiaxed‐type structure with fine, continuous selected area diffraction (SAD) patterns, until Nb concentration reaches 9 at.%. The microstructural changes of Nb‐alloyed Al layer results in smooth interface roughness, so that we could achieve a high TMR ratio. Resistance decreased from 900 Ω to 220 Ω and barrier height decreased from 1.62 eV to 0.847 eV at 9.26 at.% Nb. We speculated that the reduction of junction resistance of the MTJ with Nb‐doped Al‐oxide barrier was due to Nb d states formation in the band gap. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of magnetic field annealing on magnetic properties and microstructure of Nd‐Fe‐B‐Ti‐C based nanocomposite permanent magnet
Authors: Ishii Rintaro , Yasuda Hideyuki , Miyoshi Toshio , Kanekiyo Hirokazu , Hirosawa Satoshi 
Published: December 2007

AbstractRapidly solidified ribbons of Nd9Fe73B12.6C1.4Ti3Nb1 were annealed with or without a static magnetic field of 10 T. The remanence (Br) of the ribbon annealed with the magnetic field was higher than that of the ribbon annealed without the magnetic field. Improved magnetic properties of the ribbon annealed with the magnetic field may be attributed to a uniformly fine grain size. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GISAXS study of the alignment of oriented carbon nanotubes grown on plain SiO2/Si(100) substrates by a catalytically enhanced CVD process
Authors: Mane Mane J. , Cojocaru C. S. , Barbier A. , Deville J. P. , Thiodjio Sendja B. , Le Normand F. 
Published: December 2007

AbstractAmong the contributions in this issue of pss (a) two articles were selected as Editor's Choice [1, 2]. Rudziński et al. [1] study the influence of substrate orientation on GaN film growth on 4H‐SiC, suggesting a model for the formation of rows of threading edge dislocations and directional cracking in these films.The cover picture is extracted from the article by Mane Mane et al. [2]. The picture illustrates the successful combined use of the GISAXS technique within the Effective Layer Born Approximation (ELBA) and the Distorted Wave Born Approximation (DWBA), in conjunction with the description of diffusing entities as C tubes, Co cylinders and intermixed Co–C clusters, in order to calculate the full experimental GISAXS images of uncorrelated carbon nanotubes grown on cobalt catalyst. The strong contribution of the surface reflectivity to the collected GISAXS signal is emphasized in the paper. Compare the experimental GISAXS pattern of carbon nanotubes in the upper left panel to the ELBA images considering Co cylinders and C tubes with (upper right) and without (lower left) intermixed C–Co tubes. The lower right panel shows the resulting DWBA pattern.The first author, Dr. Jeannot Mane Mane, graduated with a Ph.D. from the University Henri Poincaré in Nancy in 1993. He currently holds a Senior Lecturer position at the University of Yaounde I (Cameroon) as well as a research position at the CNRS Institut de Physique et Chimie des Matériaux de Strasbourg (France). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Processes involved in the high‐temperature thermoluminescence of a Mn2+‐doped MgF2 phosphor
Authors: Secu M. , Jipa S. , Secu C. E. , Zaharescu T. , Georgescu R. , Cutrubinis M. 
Published: December 2007

AbstractThe thermoluminescence (TL) glow curve recorded after gamma‐irradiation at room temperature of Mn2+‐doped MgF2 phosphor shows two intense TL peaks at 364 K and 420 K accompanied by several weaker peaks up to 600 K. The TL spectra have shown Mn2+ luminescence at about 560 nm. The 364 K TL peak disappears after one day of storage, and so is probably related to the recombination of carriers from some shallow traps. Based on thermal bleaching and optical bleaching (in the 260 nm F‐centre absorption band) experiments, the 420 K TL peak was ascribed to the thermally activated recombination between an F‐centre and a hole centre trapped in the neighbourhood of the Mn2+ impurity which results in Mn2+ luminescence. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Luttinger–Ward method applied to the 2D Coulomb gas
Authors: Agnihotri M. P. , Apel W. , Weller W. 
Published: December 2007

AbstractWe review the Luttinger–Ward method and show how one can combine it with the theory of Baym and Kadanoff in order to get conserving approximations in many‐body perturbation theory. We solve the variation procedure numerically using an ansatz for the selfenergy in the case of the two‐ dimensional Coulomb problem. Comparison with results of the traditional iteration of the selfconsistency equation yields satisfactory agreement for parameters where the iteration converges. The extremalization of the Luttinger–Ward functional works beyond that point. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐frequency 1/f noise in relaxor ferroelectric PMN–PZT
Authors: Gridnev S. A. , Tsotsorin A. N. , Kalgin A. V. 
Published: December 2007

AbstractThe dielectric properties of relaxor ferroelectric ceramics (1 – x)PbMg1/3Nb2/3O3–(x)PbZr0.53Ti0.47O3(PMN–PZT) have been studied at various frequencies in the temperature range of the diffuse phase transition. Dispersion of the complex dielectric permittivity ε * characteristic for relaxors was revealed in the vicinity of the ε * maximum temperature Tm. It has been determined that low‐frequency 1/f noise in the studied system is mainly caused by the polarization relaxation in local polar regions and the spectral density of the noise depends on the relaxor composition and temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffusion mechanism of implanted Be in GaAs
Authors: Koumetz S. D. , Pesant J.‐C. , Dubois C. 
Published: December 2007

AbstractThe transient enhanced diffusion of low and high dose implanted beryllium in undoped gallium arsenide during post‐implant rapid thermal annealing in the temperature range of 700–900 °C for 60–240 s has been studied and successfully simulated by the kick‐out diffusion model, involving singly positively charged Be interstitials and doubly positively charged Ga self‐interstitials. Using the “plus one” approach for Ga interstitial generation after implantation with the local Ga interstitial sink concept as well as the appropriate initial and boundary conditions for involved mobile species, and taking into account Fermi‐level and built‐in electric field effects, the obtained partial differential equations have been solved numerically by means of an explicit finite difference method. The thermal equilibrium concentrations and the diffusivities of Be and Ga interstitials, all as a function of temperature, have been deduced from the fits of the experimental profiles obtained by the secondary ion mass spectrometry technique. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control synthesis of iron oxide nanospheres using solution chemistry
Authors: Wu M. Z. , Lee H. , Hwang S. Y. 
Published: December 2007

AbstractA facile solution chemistry approach to the batch synthesis of magnetite nanocrystals is developed. By using different starting materials, the control of particle size and size distribution can be achieved. Detailed investigations into the morphology and size distribution of the final products were carried out with the aid of field emission scanning electronic microscopy (FESEM). The crystal structure was studied by powder X ray diffraction (XRD). Vibrating sample magnetometer (VSM) was used to study the magnetic properties of these sphere‐like products. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In vivo and in vitro antitumor activity of doxorubicin‐loaded magnetic fluids
Authors: Park S. I. , Lim J. H. , Hwang Y. H. , Kim K. H. , Kim S. M. , Kim J. H. , Kim C. G. , Kim C. O. 
Published: December 2007

AbstractDoxorubicin‐loaded magnetic particles with lecithin and polyethylene glycol as an interlayer were synthesized by multi‐step process of high temperature thermal decomposition and ultrasonic, respectively. The change of particle size and the magnetic property were investigated for the estimation of the carrier characteristic with doxorubicin addition. And, the loading efficiency of drug and the loaded drug released fraction were discussed for the estimation of drug effect. Also, the remedial efficiency of adsorbed drug on the magnetic nanoparticle was investigated by comparing the cytotoxicity of tumor cell between bare‐ and doxorubicin‐loaded magnetic nanoparticles. And, in‐vivo test was performed to estimate the effect of anticancer therapy by using C57BL/6 mice as an animal sample. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Etch characteristics of magnetic tunnel junction stack using a high density plasma in a HBr/Ar gas
Authors: Min Su Ryun , Cho Han Na , Noh Su Jin , Kim Kee Won , Seo Sun Ae , Chung Chee Won 
Published: December 2007

AbstractEtch characteristics of magnetic tunnel junction (MTJ) stack masked with TiN thin films were investigated using an inductively coupled plasma reactive ion etching in HBr/Ar gas for the application of magnetic random access memory. The effect of HBr gas concentration on the etch profile of MTJ stacks was examined. As HBr gas concentration increased, the sidewall angles of etched patterns of MTJ stacks were slightly improved. The effect of etch parameters including coil rf power, dc‐bias voltage, and gas pressure on the etch profile of MTJ stack was explored. At low coil rf power, low dc‐bias voltage, and high gas pressure, the etching of MTJ stack displayed better etch profile. A high degree of anisotropic etching of MTJ stacks without redeposition was achieved using HBr/Ar gas at the optimized etch conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Property of nitrogenated tetrahedral carbon on magnetic head prepared by filtered cathodic arc deposition
Authors: Mingchu Yang , Gonzaga Leonard , Bo Liu 
Published: December 2007

AbstractNitrogenated tetrahedral carbon films were prepared by filtered cathodic arc deposition. Raman spectroscopy analysis shows N incorporation increases the clustering of the sp2 phase, Nanoindentaion shows the hardness reduction caused by N incorporation can be compensated by optimization of C ion energy in the deposition. Ta‐C:N films shows higher extinction coefficient and less transparency. The good morphology of films implies ta‐C:N overcoat has good coverage on magnetic head. Corrosion experiment reveals ta‐C:N overcoat has better anti‐corrosion performance. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Texture in die‐upset Nd‐Fe‐B magnet produced using HDDR‐treated particles
Authors: Lee J. I. , Kwon H. W. , Choi G. S. 
Published: December 2007

AbstractThe die‐upset Nd15Fe77B8 material consisting of near single domain Nd2Fe14B grains was prepared using the HDDR‐treated material. Texture (c‐axis alignment) of the Nd2Fe14B grains in the die‐upset HDDR material was investigated, and compared with that in the die‐upset melt‐spun Nd‐Fe‐B material. The die‐upset HDDR material showed a texture, in which the easy magnetisation c‐axis of the Nd2Fe14B grains was aligned parallel to the compression direction. The texture obtained from the die‐upset HDDR material was much poorer with respect to that from the die‐upset melt‐spun material (Nd13.5Fe80Ga0.5B6). The poor texture in the HDDR material was due to the greater grain size of the material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
LC filter‐type magnetoimpedance sensors with multilayer film structure
Authors: Tanaka K. , Shin K. H. , Uchida H. , Inoue M 
Published: December 2007

AbstractWe have investigated the basic characteristics and applicability of the LC high pass filter configuration for signal conditioning of the magnetoimpedance (MI) sensor. The MI sensor elements were fabricated through photolithography and lift‐off process of CoZrNb/Au/CoZrNb multilayer, and the LC high pass filters were configured using the fabricated sensor elements and surface mount capacitors. To confirm the high frequency performance of the sensor elements, frequency dependence of the impedance was measured as function of external magnetic field using a network analyzer. The output increased to reach the peak value with increase of magnetic field to around 20 Oe, which was almost the same with the anisotropic field of the multilayer film pattern, and the measured maximum change ratio is 49%. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A magnetic heat pump with porous magneto caloric material
Authors: Vuarnoz D. , Kitanovski A. , Diebold M. , Gendre F. , Egolf P. W. 
Published: December 2007

AbstractAt present magnetic refrigeration shows a realistic potential to penetrate into some niche markets in the field of cold and hot “production”. It is well known that a refrigerator for cooling and a heat pump for heating are machines based on the same principle. A small review on magnetic heat pump studies is outlined and a simple engineering calculation scheme to determine the coefficient of performance for a magnetic heat pump with a rotary porous structure heat exchanger is presented. Magnetic heat flux line distributions are calculated by a 2‐d finite element method numerical simulation program with the objective to obtain high field's μ0H with not too heavy permanent magnets assemblies. The porous structures are geometrically optimised to obtain maximal magnetic field inductions. It is shown that for a water/ethylene‐glycol magnetic heat pump the coefficient of performance is higher than that of a conventional heat pump. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of nanostructure (In15Sb85)100–xZnx thin films
Authors: Ou Sin‐Liang , Kuo Po‐Cheng , Sheu Shu‐Chi , Wu Ting‐Hau , Chiang Don‐Yau , Tang Wei‐Tai 
Published: December 2007

AbstractThe (In15Sb85)100–xZnx films (x = 0∼13.7) were deposited on nature oxidized Si wafer at room temperature by dc co‐sputtering of Sb target and InZn composite target. Effects of Zn content on the optical properties of (In15Sb85)100–xZnx film were examined by X‐ray diffraction and reflectivity thermal analyzer. It is found that the crystallization activity energy of the film is increased with Zn content, this indicates that the thermal stability of amorphous state is improved by doping Zn. The structure of as‐deposited (In15Sb85)100–xZnx film was amorphous and it would transform to Sb, InSb, and ZnSb coexisting phases after annealing at 250 °C. The reflectivity of annealed film was higher than that of as‐deposited film. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large area magnetic domain imaging of magnetite films with Spin‐SEM
Authors: Kaji Eisaku , Subagyo Agus , Sueoka Kazuhisa 
Published: December 2007

Abstract The surface crystallographic structure and magnetic structure of magnetite thin films epitaxially grown on a MgO(001) substrate were investigated by means of a scanning tunnelling microscope (STM), magnetic force microscope (MFM) and Spin‐polarized scanning electron microscopy (Spin‐SEM). The STM investigation and MFM measurement were performed in‐situ and in an ambient condition, respectively. After exposing the sample to air, a Spin‐SEM image was acquired. Spin‐dependent contrasted SEM images could be obtained after cleaning the sample surfaces. The cleaning procedure is annealing the sample at 250 °C in an ultra high vacuum (UHV) below 3 x 10–8 Pa for 3 hours. The STM observation indicates the thin films have antiphase domains and the observed MFM images reflect a cease in micromagnetic domain structures. Spin‐SEM images indicate that large‐scale magnetic inhomogeneity of a few μm is the inhomogeneity of the perpendicular magnetic moments of the films. Due to the spatial resolution limitation of our Spin‐SEM system, the correlation between the fine and coarse magnetic structures of the thin films induced by the antiphase domain boundaries is not clear, however, we have suggested the annealing process alone in a UHV makes the spin configuration of the thin films visible using a conventional Spin‐SEM system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomalous magnetoimpedance in Co–Fe–Al–O thin films
Authors: Tuan L. A. , Phan M. H. , Ha N. D. , Kim C. G. , Kim C. O. , Yu S. C. 
Published: December 2007

AbstractThe high‐frequency giant magnetoimpedance (GMI) effect in a Co47.5Fe21.9Al17.2O15.2 thin film was systematically investigated. In the frequency range of 100–500 MHz, GMI profiles showed a double‐peak characteristic, reflecting an evident existence of the transverse magnetic anisotropy in the film, which coincided with the magnetization data. Interestingly, there was an anomalous transformation in the GMI profile from “positive” to “negative” and this was associated with the complex phase transformation of permeability. The GMI ratio decreased with decreasing film‐thickness, due to an increase of the electrical resistivity and a decrease of the magnetic softness. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of film thickness on the electrical and magnetic properties of Co–Fe–Al–O films
Authors: Phan M. H. , Tuan L. A. , Ha N. D. , Phan T. L. , Kim C. G. , Kim C. O. , Yu S. C. 
Published: December 2007

AbstractInfluence of film thickness (t) on the electrical and magnetic properties of Co–Fe–Al–O films has been systematically investigated via means of vibrating sample magnetometry (VSM), permeability spectra and magneto‐optical Kerr effect (MOKE). It is found that the electrical resistivity (ρ) decreases as the film thickness increases; ρ = 412.5 µΩcm for the t = 600 nm sample decreases to ρ = 368.2 µΩcm for the t = 1200 nm sample. The coercive force, measured along the easy‐axis direction, decreases as the film thickness increases. Interestingly, along the hard‐axis magnetization direction, the magnetic hysteresis loop is reversed and the coercive force is negative for the t = 600 and 800 nm samples. However, this peculiar feature disappears as t reaches 1200 nm, which is probably attributed to the microstructural change with respect to changes of film thickness. At a frequency of 1GHz, the hard‐axis effective permeability decreases from 1252 to 1000 as the film thickness increases from 600 to 1200 nm, respectively. The VSM and MOKE results reveal an increase in magnetic anisotropy in the near‐surface region of the film. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructure of single stage hot deformed anisotropic Nd–Fe–B magnets
Authors: Tian Hao , Li Ying , Zhu Mingyuan , Jin Hongming , Jin Dongzhe 
Published: December 2007

AbstractSingle stage hot deformation (SSHD) process is an effective method to fabricate anisotropic magnet. In this study, the influences of particle size and hot press temperature on microstructure were discussed, respectively. Anisotropic magnetic properties are affected by SSHD process conditions through the changing the microstructure of the magnets. SEM investigation shows that, good magnetic properties related with suitable geometric shapes of the grains and their better alignment. Good alignment could be obtained when the particle size of raw material MQPA powders is between 45∼100 μm and the SSHD magnet is made at 700 °C. When the deformation temperature is below the melting temperature of Nd rich phase, the platelet‐shaped Nd2Fe14B grains could not be formed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Current status and future of magnetic heads for HDD
Authors: Terunuma K. 
Published: December 2007

AbstractThe rapid growth in consumer electronics application requires higher capacity data storage. For hard disk drive (HDD), many new technologies, such as media, heads, head‐disk interface (HDI), pre‐amp. and so on, have been introduced in order to increase the recording density. This paper focus on magnetic head technologies, such as materials, structures, fabrication process and head performance for HDD. For read heads, tunneling magnetoresistive (TMR) heads have come successively to replace giant magnetoresistive (GMR) heads. Barrier materials have been studied to obtain higher magnetoresisance (MR) ratio with lower resistance area product (RA). AlOx have been used as barrier for 100–120 Gb/in2 TMR heads. MgO barrier shows significantly large MR ratio and is also workable to TMR heads as AlOx one. For longitudinal magnetic recording (LMR) writer, recording performance has been improved with reducing yoke length and coil turns and changing to pole materials with higher saturation magnetization (Bs). Perpendicular magnetic recording (PMR) is introduced for over 120 Gb/in2. Combination between head and medium is much more important in PMR than LMR. The magnetic head is still one of the key component of HDD and is expected to be going to further promote the redording density and performance of HDD in the future. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observation of multiple transitions on permalloy ring by magnetic force microscopy
Authors: Lin L. K. , Kuo C. Y. , Ou J. Y. , Chang C. C. , Chang C. R. , Horng Lance , Wu J. C. 
Published: December 2007

AbstractWe present a study of magnetization reversal on microstructured permalloy thin film rings using a magnetic force microscopy in the presence of external magnetic fields up to 540 Oe. Permalloy rings with fixed thickness/outside diameter of 23 nm/5 μm and inside diameter of 2.2 and 2.6μm, respectively, were fabricated by using standard electron beam lithography through a lift‐off process. Four transitions during magnetization reversal were observed on the one with 2.2 μm inside diameter, in which the magnetization was evolved from onion to vortex‐pair, vortex‐pair to vortex, vortex to vortex‐core, vortex‐core to reverse onion state. The remanent state was flux closure vortex state. A similar magnetization evolution occurred on the one with 2.6 μm inside diameter except that the remanent state was vortex pair. The numerical simulation results using OOMMF showed good agreement with the experimental results. These multiple stable states during the magnetization reversal may provide an excellent opportunity for developing multi‐bit storage cells. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic properties of spin valves having extremely thin underlayers
Authors: Kim Jiwon , Jo Soonchul , Kim Sang Yoon , Ko Hoon , Lee Chang‐Woo 
Published: December 2007

AbstractMagnetic properties of spin valve elements having Mo(N) and Ta(N) underlayers were studied by varying their thickness. Spin valve structure was Si/SiO2/Underlayer(tÅ)/NiFe(21 or 42Å)/CoFe(28Å)/Cu(22Å)/CoFe(18Å)/IrMn(65Å)/Ta(25Å). Spin valve elements having exteremely thin Mo(N) and Ta(N) underlayers showed high MR ratio of about 7 ‐ 8%. Annealing of such spin valve elements having underlayer thickness of 7 to 8 Å showed comparable behavior with the spin valve elements with thicker (35Å) underlayer, which can be utilized to reduce overall device thickness. Also, it was found that Mo(N) underlayers for spin valve elements may be used as diffusion barriers between Si substrate and ensuing active spin valve layers, simultaneously. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)