Notification:
We are currently experiencing intermittent issues impacting performance. We apologize for the inconvenience.
By Topic

Magnetics Conference, 2006. INTERMAG 2006. IEEE International

Date 8-12 May 2006

Filter Results

Displaying Results 1 - 25 of 1004
  • Application of spin-torque diode effect to the analysis of spin-transfer switching in MgO-based magnetic tunnel junctions

    Publication Year: 2006 , Page(s): 1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (673 KB) |  | HTML iconHTML  

    Multilayers of buffer/Pt-Mn/Co-Fe/Ru/Co60Fe20B20 (3.2 nm)/Mg (0.4 nm)/MgO (0.6 nm)/ Co61Fe7Ni15B15 (3 nm)/Ta/Ru is prepared on thermally oxidized Si substrates by UHV sputtering system (ANELVA C7100). The free layer Co-Fe-Ni-B has low magnetostriction, which is important characteristics for MRAM with high endurance for write/erase cycles. After annealing at 330degC, the film was patterned into 80 nm x 170 nm ellipsoids. The observed R-Hcurves showed sharp switching between low and high resistance states. The MR ratio was about 80% and resistance-area product was about 2 Omegam2. STS effect for MTJ is applied to evaluate the spin-transfer switching. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mutual Phase-Locking of Microwave Spin Torque Nano-Oscillators

    Publication Year: 2006 , Page(s): 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (202 KB) |  | HTML iconHTML  

    The spin torque effect is a consequence of the continued, required scaling of magnetic devices. The output of this device can be frequency modulated, phase-locked to a stable external source, and mutually phase-locked to a neighboring oscillating contact. Measurements further indicate that the oscillators are also phase-locked during the coincidence of their frequencies. We have verified that the combined output power during locking is proportional to the square of the sum of the individual oscillators' voltage outputs as expected for the combination of two coherent signals. Furthermore this data implies a possibility to significantly increase oscillator power output from a micro-scale device by utilizing an array of N phase-locked oscillators with combined output power proportional to N2. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic excitations of nanomagnet magnetization driven by spin-polarized current

    Publication Year: 2006 , Page(s): 3
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (347 KB) |  | HTML iconHTML  

    A current of spin-polarized electrons injected into a metallic nanomagnet exerts torque on the magnetization and may excite magnetization autooscillations. The aim of present work is to study spectral and transient properties of such excitations. We study current-driven excitations in a permalloy (Py) elliptical nanomagnet. We also make time-resolved measurements of the ac voltage generated by the current-driven excitations using a storage oscilloscope. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Switching by sub-nanosecond current pulses using spin angular momentum transfer

    Publication Year: 2006 , Page(s): 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (697 KB) |  | HTML iconHTML  

    The spin-transfer switching performance of spin valve nanopillars composed of PtMn17.5/CoFe1.8/Ru8/CoFe2/Cu3.5/CoFe1/NiFe1.8 is measured in this study at current pulse durations of 0.1-10 ns and temperature range of 40-300 K. Results show that the switching speed accelerates marginally when cooling, with a slightly better reproducibility at low temperature. A static field applied along the hard axis however can drastically accelerate the switching, increasing the efficiency of both DC current and pulsed current. This can be attributed to the influence of a noncollinear initial state, and becomes significant when the field is greater than typically a quarter of the anisotropy field. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Current-induced magnetization reversal in nanopillars with perpendicular anisotropy

    Publication Year: 2006 , Page(s): 5
    Cited by:  Papers (7)  |  Patents (27)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    In the present article, we describe our experiment demonstration of magnetic reversal and domain wall motion in driven by spin-currents in devices and wires with both the reference and free layer possessing perpendicular magnetic anisotropy.Two types of multilayer structures were designed such that the magnetic layers had perpendicular anisotropy. These were (bottom lead/ [Co/Pt]/[Co/Ni]/Cu/[Co/Ni]/ top lead) and (bottom lead/ [Co/Pt] Cu/[Co/Pt]/ top lead) sample structures. For the Co/Ni structure, the reference layer is a composite Co/Pt and Co/Ni multilayer to enhance the anisotropy and the free layer is a Co/Ni multilayer. E-beam lithography was used to define nanopillars with different shape (circle, hexagon and square) and different size. (diameters ranging from 1600 nm to 50 nm).The minor hysteresis loop shows the reversal of only the free layer, which is offset by 650 Oe from the origin due to the average dipolar field from the lower layer that favors parallel alignment. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Current-driven magnetization switching in CoFeB/MgO/CoFeB magnetic tunnel junctions

    Publication Year: 2006 , Page(s): 6
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (79 KB) |  | HTML iconHTML  

    The current-driven magnetization switching in CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) with various free layer materials including synthetic structure was studied in this paper. The MTJ films were deposited on SiO2/Si substrates using RF magnetron sputtering. The tunnel magnetoresistance (TMR) ratios and current-voltage (I-V) characteristics of the the MTJs were measured at room temperature using a dc four-probe method and with a magnetic field of up to 1 kOe. The TMR ratio and the current-driven magnetization switching at critical current densities were shown as a function of annealing temperature for two types of MTJs with different free layer. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stacking faults in perpendicular media; the relationship to anisotropy dispersion

    Publication Year: 2006 , Page(s): 7
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (75 KB) |  | HTML iconHTML  

    This paper investigates the effect of stacking faults in CoPt media using a simple model based on empirical characterization of micromagnetic calculations. The presence of stacking faults give rise to a reduction of the effective value of HK via the introduction of local fcc planes. The analysis shows that the statistical distribution of the fcc planes among the grains can give a significant contribution to the width of the effective HK dispersion. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Oxide mobility enhancement due to bias sputtering in perpendicular recording media

    Publication Year: 2006 , Page(s): 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (663 KB) |  | HTML iconHTML  

    This study addresses some consideration of oxide mobility in two types of oxide composite perpendicular media A (CoCrPt-SiO2) and B (FePt-MgO). The effects of bias sputtering on the morphology of the deposited composite film was examined. Results show that although the preferential sputtering seems different, the enhanced grain separation in the biased films is similar for the two media, which suggests that biasing is generally effective in driving the segregation. This is ascribed to an increase in Ar ion bombardment of the substrate during bias sputtering, which helps to increase mobility of the oxide molecules on the growing surface such that they reach grain boundaries. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetic and Recording Characteristics of Reactively Sputtered CoPtCr-(Si-O, Ti-O and Cr-O) Perpendicular Media

    Publication Year: 2006 , Page(s): 9
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (286 KB) |  | HTML iconHTML  

    In this work, CoPtCr-oxide films were deposited with three types of oxide additives(Si-O, Cr-O, Ti-O). Their magnetic, grain morphological properties and oxidation kinetics were systematically studied by varying oxygen reactive sputter conditions and were correlated with PMR performance. CoPtCr-oxide media has been reported to have small grains with good magnetic decoupling for perpendicular recording media. More detailed recording performance including magnetic write width and thermal stability are discussed for all the media at different PO2. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Magnetic Recording Layer Thickness on Media Performance in CoCrPtO Perpendicular Media

    Publication Year: 2006 , Page(s): 10
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (722 KB) |  | HTML iconHTML  

    In this study, the effect of magnetic recording layer thickness on media performance in CoCrPtO perpendicular media was investigated. The thin films were reactively sputter-deposited on NiP-coated Al substrates. Ru/Ta was used as an interlayer and the total thickness of the synthetic antiferromagnetically-coupled SUL was 140 nm. The CoCrPtO layer thickness was varied from 2 to 27 nm. Saturation magnetization (Ms) of the CoCrPtO layer, obtained from a slope of saturation magnetization per unit area versus media thickness (tMAG), was 450 emu/cm3. The film orientation and microstructure were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Polar magneto-optic Kerr effect (MOKE) magnetometer and vibrating sample magnetometer (VSM) were used to measure the magnetic properties. Recording performance was evaluated by using a spin-stand tester with a single-pole-type writer and a GMR reader. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel Approach to Reduce Grain Size in CoCrPt-Oxide Perpendicular Recording Media

    Publication Year: 2006 , Page(s): 11
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1367 KB) |  | HTML iconHTML  

    This paper presents an alternative approach to reduce the grain size in recording media probably without affecting the anisotropy constant so much. It can be seen that the medium deposited on the new underlayers shows a smaller average grain size (6 nm) as well as a narrow grain size distribution (25%) as compared to 8 nm and 35% that is observed for the medium on conventional underlayer. The grain sizes are measured from center-to-center and the repoorted values include grain boundary as well. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Formation of Grain- Isolated Co80Pt20 Magnetic Films for Granular-Type Perpendicular Media

    Publication Year: 2006 , Page(s): 12
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (645 KB) |  | HTML iconHTML  

    This paper discusses the formation of the Co80Pt20 film with isolated grain structure in order to achieve excellent recording performance of the granular-type perpendicular media. Results show that the uniaxial anisotropy constant Ku and saturation magnetization Ms are 1.15times102 (erg/cc) and 1100 (emu/cc), respectively. The coercivity Hc increases significantly by increasing Ru underlayer thickness. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • EBL thickness and transition parameter in perpendicular oxide media

    Publication Year: 2006 , Page(s): 13
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (787 KB) |  | HTML iconHTML  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pt-Cr alloy intermediate layer for granular perpendicular media

    Publication Year: 2006 , Page(s): 14
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (935 KB) |  | HTML iconHTML  

    In this paper, fabrication of intermediate layer (IML) with a Pt-Cr binary alloy system for granular perpendicular media was discussed. Kerr magnetometer was used to obtain hysteresis loops of the co-sputtered Pt-Cr alloy IMLs. The saturation magnetizations Ms and the uniaxial magnetic anisotropy energy Ku were measured with a vibrating sample magnetometer and a torque magnetometer with an applied field of 5 T, respectively. The microscopic structures were examined with transmission electron microscopy (TEM) and the recording performance was characterized by the media SNR at 400 kFCI as measured using a SPT/GMR head. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel Electroless CoNiFe Soft Magnetic Underlayer on a Si Disk Substrate for Perpendicular Recording Media

    Publication Year: 2006 , Page(s): 15
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (930 KB) |  | HTML iconHTML  

    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. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Highly-Oriented High-Bs Fe-Co Soft Underlayer for High Density Perpendicular Recording Media

    Publication Year: 2006 , Page(s): 16
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1166 KB) |  | HTML iconHTML  

    Co-Pt based granular films have been investigated as a recording layer for recent perpendicular magnetic recording media. To induce c-axis crystal orientation of the recording layer at room temperature, relatively thick intermediate layers such as Ru and Ru/Pt are used on an amorphous or a granular soft underlayer (SUL). For high density perpendicular recording, it is desirable that the distance between a single-pole head and a SUL is short. Consequently, it is necessary to enhance the crystal orientation and to reduce the film thickness of the intermediate layer. On the other hand, a high-Bs SUL is needed to reduce the film thickness from the viewpoint of industrial production. I tried to prepare an Fe-Co soft underlayer with a high-Bs of 2.4 T and a high crystal orientation to solve these problems simultaneously. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Enhancement of interlayer exchange coupling for antiparallel coupled soft magnetic underlayers using FeCoB amorphous material

    Publication Year: 2006 , Page(s): 17
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (437 KB) |  | HTML iconHTML  

    This presentation reports the enhancement of interlayer exchange coupling in a stacked soft magnetic underlayer produced by DC magnetron sputtering at room temperature. Grazing incidence X-ray reflective technique, vibrating sample magnetometry and longitudinal Kerr analysis are used to characterize the obtained films. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Side Erasure Analysis in Perpendicular Recording Media Using Dynamic Read-Back Microscopy

    Publication Year: 2006 , Page(s): 18
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    A spin-stand level dynamic read-back microscopy (DRM) technique offers ease of use and full compatibility with standard media parametrics testing. We designed and implemented a DRM tester based on a LeCroy DDA5005 oscilloscope and a Guzik spin-stand. Using a DRM, we investigated the effect of magnetic exchange coupling on side erasure of CoCrPt-SiO PMR media. Exchange was controlled by varying the oxygen partial pressure during deposition. The paper show tracks after a progressive edge-trimming from the both sides using a low DC-negative erase current. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetophotonic crystals

    Publication Year: 2006 , Page(s): 19
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (44 KB) |  | HTML iconHTML  

    In much the same way that semiconductor crystals affect the propagation of electrons, photonic crystals (periodic composites of macroscopic dielectric media of different refractive index) affect the propagation of light, providing a new mechanism to control and manipulate the flow of light. When the constitutive material of PCs is magnetic, or even only a defect introduced into the periodic structure is magnetic, the resultant PCs (let us simply refer to as magnetophotonic crystals (MPCs) hereafter) exhibit unique optical and magneto-optical responses: The strong photon confinement associated with the magnetic defect can be exploited to enhance and optimize magneto-optical (MO) effects and optical non-linearity of existing materials. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Length Scales of Magnetic Correlations in √e¬μ-Co Nanoparticle Assemblies using Small Angle Neutron Scattering

    Publication Year: 2006 , Page(s): 20
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1373 KB) |  | HTML iconHTML  

    This article presents experiments on the determination of the length scales of magnetic correlation in ε-Co nanoparticle assemblies using SANS (small angle neutron scattering). In this experiment a 0.5 nm neutron beam was passed through a sealed sample containing a dense assembly of the nanoparticles, and the scattered intensity was collected with two-dimensional detector. Data were collected with magnetic fields ranging from 0 to 5 T, which were applied perpendicular to the neutron beam. The temperature varied between 5 and 275 K. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Self-Assembly and Magnetic Properties of MnO Coated FePt Nanoparticles

    Publication Year: 2006 , Page(s): 21
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    This paper reports on the synthesis and self-assembly of FePt/MnO core/shell nanoparticles. The enhanced magnetic properties of FePt nanoparticles with MnO coating is shown. Results also demonstrated the suppression of aggregation of MnO coated FePt nanoparticles during the annealing process. The magnetic moment of the FePt nanoparticles is significantly enhanced with the MnO shell. Also, the room temperature hysteresis loops curves reveal that the annealed FePt nanoparticles without the MnO shell have a large coercivity around 14 kOe, while FePt nanoparticles with the MnO shell show a sheared loop with a small coercivity about 3 kOe. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the L10 Ordering Kinetics In Fe-Pt Nanoparticles

    Publication Year: 2006 , Page(s): 22
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (574 KB) |  | HTML iconHTML  

    In this presentation, we quantify the minimum times required to obtain the L10 phase in in-flight annealed FePt nanoparticles. After their gas phase preparation by means of inert gas condensation in Ar, the particles are carried with a continuous Ar gas flow through an annealing furnace (diameter = 38 mm, length = 0.7 m). The gas flow rate and pressure are typically 100 sscm and 1 mbar, respectively. We have calculated the velocity and temperature profiles of the Ar gas along the annealing furnace by means of a computational fluid dynamics software package ("Fluent"), since at typical particle sizes of some 5 nm, the particles are in thermal equilibrium with the carrier gas within less that a millisecond, the obtained results can be immediately transferred to the particles themselves. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Local Structure of Directly Synthesized L10 FePt Nanoparticles

    Publication Year: 2006 , Page(s): 23
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1930 KB) |  | HTML iconHTML  

    The aim of the paper is to study the structural properties of the FePt particles synthesized at 200deg and 300deg C by using the XRD and XAFS techniques and the mechanism behind partial ordering has been proposed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Steering the magnetism of low-dimensional Fe-Pt nanostructures through coordination

    Publication Year: 2006 , Page(s): 24
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1233 KB) |  | HTML iconHTML  

    A complete understanding is still missing. All models, however, emphasize the importance of Fe-Pt coordination and the induced moments in Pt-atoms for the magnetic anisotropy and the formation of an effective exchange field. We recently performed XMCD measurements on a Fe50Pt50 monolayer alloy grown on vicinal Pt(997). The surface alloy exhibits high coercive fields comparable to those found in 3D samples exhibiting L10 structure. These results suggest that, in contrast to theoretical work, the third dimension in the L10-phase is not necessarily the key for the understanding of its hard magnetic properties. We therefore studied the magnetism of low-dimensional Fe structures as a function of Fe-Pt as well as Fe-Fe coordination. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Microwave Responses of the FePt Nanoparticles in Solution Phases

    Publication Year: 2006 , Page(s): 25
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (590 KB) |  | HTML iconHTML  

    Summary form only given. Microwave responses for the monodisperse FePt nanoparticle was observed in this experiment. The monodisperse FePt with particle size of around 3-5 nm was prepared by chemical synthesis. The process was given by Pt(acac)3 and Fe(acac)3 in solution phase and stabilized the monodisperse FePt nanoparticle in aqueous and organic solution phases. The 45 MHz~50 GHz microwave signals were transmitted into thiol and organic solution by a single end probe. The reflection responses from the monodisperse FePt nanoparticle in solution were detected by the microwave probe. In terms of the short, open and reflection signals, the permittivity of monodisperse FePt nanoparticle was obtained by the single end microwave probe. Figure 1 and 2 configured the permittivity of the distilled water in theory and experiment. Figure 3 showed the permittivity of FePt nanoparticle in different particle sizes. We observed that the microwave signal was sensitive to solution phase and the particle size in some specific frequency bands. The report will configure their microwave responses, particle size and magnetic properties. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.