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  • 1
    Electronic Resource
    Electronic Resource
    Magnetohistory effects and spin reorientations of Nd3Fe29−xTx and Nd3Fe29−xTxN4 (T=V and Cr) compounds : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5170-5172 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The novel compounds Nd3Fe29−xTx (T=V and Cr) have been successfully synthesized. Their x-ray patterns can be indexed with a monoclinic symmetry and the A2/m space group. The Curie temperatures of Nd3Fe29−xTx are 455 and 413 K for T=V and Cr, the saturation magnetization at 4.2 K and room temperature are 54.7 and 46.8 μB/f.u. for T=V and 49.9 and 32.2 μB/f.u. for T=Cr, and the anisotropy fields at 4.2 K and room temperature are 12.8 and 2.4 T for T=V and 9.1 and 1.2 T for T=Cr, respectively. The spin reorientations of the easy magnetization direction of Nd3Fe29−xTx are observed at around 230 K for T=V and 135 K for T=Cr, respectively. After nitrogenation the relative volume expansion was about 6%, Curie temperature of each nitride increased about 50%, and the transition temperature Tsr of the spin reorientations of the nitride also increased 145 K for T=V and 250 K for T=Cr, respectively, compared with its parent compound. Nitrogenation resulted in remarkable improvements in the saturation magnetization and anisotropy fields at 4.2 K and room temperature. Magnetohistory effects for Nd3Fe29−xTx and Nd3Fe29−xTxN4 (T=V and Cr) in a low field have been observed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365160
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and magnetic properties of novel compounds R3(Fe, T)29 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy; T=V and Cr) (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 7450-7457 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic investigation of structure and intrinsic magnetic properties of the novel compounds R3(Fe, T)29 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy; T=V and Cr) has been performed. The lattice constants and unit cell volume decrease with increasing the rare-earth atomic number from R=Nd to Dy, except for Ce, reflecting the lanthanide contraction. The Curie temperature increases from R=Ce to Gd and decreases from Gd to Dy, respectively, with increasing atomic number and Gd3Fe29−xTx has the highest Curie temperature for each series of R3Fe29−xTx (T=V or Cr) compounds. The saturation magnetization of R3Fe29−xTx at 4.2 K decreases gradually from R=Nd to Dy with increasing atomic number, except for Ce, in each series of R3Fe29−xTx. It is suggested that the Ce ion in Ce3Fe29−xTx is valence fluctuated which leads to the unusual magnetic properties. The spin reorientations of the easy magnetization direction of R3Fe29−xTx are observed at around 230, 230, and 160 K for R=Nd, Sm, and Tb when T=V, and at around 230 and 180 K for R=Nd and Tb when T=Cr, respectively. First order magnetization processes are observed around 5.7 T for Sm3Fe26.7V2.3 and 4 T for Sm3Fe24.0Cr5.0 at 4.2 K, 2.0 T for Tb3Fe28.0V1.0, and 2.3 T for Tb3Fe28.0Cr1.0 at room temperature. A phenomenological analysis shows that the saturation magnetization of R3Fe29−xTx compounds with a low T concentration can be roughly calculated based on a combination of those of the 2:17R and 1:12 units in a ratio of 1:1. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365287
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  • 3
    Electronic Resource
    Electronic Resource
    Formation and magnetic properties of novel compounds Tb3(Fe1−xVx)29 (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3248-3252 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic investigation of the structure and magnetic properties of novel compounds Tb3(Fe1−xVx)29 (x=0.033, 0.044, 0.056, and 0.061) has been performed. The lattice parameters and Curie temperatures are obtained. The saturation magnetization of Tb3(Fe1−xVx)29 decreases but the anisotropy field increases linearly with increasing V concentration at 4.2 K and room temperature. The spin reorientations of the easy magnetization direction of Tb3(Fe1−xVx)29 occur at around 160 K. A first order magnetization process of Tb3(Fe1−xVx)29 is observed with magnetic field in the range between 2.0 and 1.6 T at room temperature. The saturation magnetization of Tb3Fe29−yVy with a low V concentration at 4.2 K can be roughly calculated based on a combination of that of the Tb2Fe17 and TbFe12−yVy units in a ratio of 1:1. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364157
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  • 4
    Electronic Resource
    Electronic Resource
    A study of metal/GaAs interface modification by hydrogen plasma (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2447-2454 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The modification of metal/GaAs interfaces by atomic hydrogen has been studied using rf plasma in a reactive ion etching (RIE) system as well as hydrogen generated in an electron cyclotron resonance (ECR) system. Current-voltage (I-V) characteristics of Au/n-GaAs Schottky devices reveal a reduction in the barrier height following the room temperature rf plasma, and a slight increase with ECR hydrogenation at elevated temperatures. More interestingly, a profound increase in the effective barrier height is seen for p-GaAs (from 0.35 to 0.84 eV for the rf plasma and 0.35 to 0.69 eV for ECR). Dopant deactivation close to the surface is observed with spreading resistance and capacitance-voltage (C-V) measurements for both conductivity types. The passivation of existing deep levels and the creation of new deep levels have been found in both H RIE treated and ECR hydrogenated GaAs. The large ideality factor n in I-V plots and large voltage intercept in 1/C2 plots suggest the formation of an insulator-like I layer. The improvement in I-V characteristics for ECR hydrogenated n-GaAs indicates the effect of H passivation on a chemically etched GaAs surface. The recovery of the hydrogenation effects has also been studied as a function of temperature, illumination, and bias-anneal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356269
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  • 5
    Electronic Resource
    Electronic Resource
    Investigations of magnetic properties and microstructure of 40Cedidymium–Fe–B based magnets : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6268-6270 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of Si, Co, and Dy2O3 on magnetic properties of sintered 40Cedidymium–Fe–B magnets was investigated and related to the microstructure through transmission electron microscopy (TEM) investigations. It is found that the decrease in iHc and Tc caused by the presence of Ce in the 40Cedidymium could partly be compensated by additives. Sintered magnets with iHc = 9.2 kOe and (BH)max=28.2 MG Oe were successfully achieved. TEM investigations show an intragranular amorphous phase within the R2Fe14B (R=Nd, Pr, or Ce) grains and three new intergranular phases at grain boundaries and junctions of the R2Fe14B grains. It is suggested that the deterioration in the magnetic hardening is closely related to these new phases as well as the low magnetic anisotropy field of the Ce2Fe14B compound. The intragranular phase is likely to act as nucleation positions for reverse magnetic domains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355420
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of low-energy argon implantation on gallium arsenide Schottky barriers (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 2371-2375 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of ion bombardment damage on the properties of Au/GaAs Schottky barriers has been studied with 10-keV Ar implanted into both n-type and p-type GaAs over the dose range 1012–1015 cm−2. Electrical characteristics determined over a wide temperature range (77–360 K) reveal a number of phenomena dictating barrier modification and carrier transport across the Au/GaAs interface: Change in Schottky barrier height due to defect levels introduced by ion damage, the very low threshold dose for barrier modification, increased series resistance, and creation of a shunt conducting path. Partial dynamic annealing of defects is also observed under high-temperature ((approximately-equal-to)200 °C) implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342801
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  • 7
    Electronic Resource
    Electronic Resource
    An investigation into the mechanism of pseudospark producing metal ion beams : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 675-677 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A multiplate pseudospark chamber, whose electrodes were fabricated with different metal materials, was designed and tested as a metal ion source. The ion beam implantation combined with Rutherford backscattering (RBS) measurement was used to understand whether these ion beams come from the anode plasma or the cathode plasma. The RBS measurements have demonstrated the following results: (1) pseudospark produced metal ion beams mainly consist of ions from the cathode materials; (2) the ion beam current increases rapidly with the pseudospark discharge voltage first and then saturates; and (3) the energy of the extracted metal ions is much less than the voltage between the anode and the cathode, therefore the high discharge voltage does not correspond to the high ion energy. A possible mechanism of pseudospark producing metal ion beams is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150257
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  • 8
    Electronic Resource
    Electronic Resource
    Resistive transition of Bi(2223) silver clamped thick film (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 5108-5111 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Detailed measurements of voltage-current (V-I) curves and magnetoresistance (R-H) for Bi(2223) thick film were carried out for various temperatures and magnetic fields. The results indicate that a flux lattice melting transition takes place as the temperature and the field are raised. This transition boundary in the (H,T) phase diagram was found to follow the irreversibility line described by the function of H=H0(1−T/Tc)3/2. Above this line, the V-I curves display a flux-flow-like character. Temperature and magnetic field dependencies of flow resistance Rf-T and Rf-H show a varied viscosity in different temperature and field ranges. Below this line, V-I curves in the low voltage region present a thermally activated flux creep property. The R-H measurements indicate that the fields at the onset and the midpoint of the magnetoresistive transition also follow a (1−T/Tc)3/2 dependence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354297
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal stability of Pd/Ge-based ohmic contacts to n-type GaAs (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 1310-1315 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructural changes that occur during high temperature annealing (450–600 °C) of Pt/Ti/Ge/Pd ohmic contacts to n-type GaAs have been studied using transmission electron microscopy (TEM). The metal layers were deposited sequentially by electron beam evaporation onto GaAs doped with Si to a level of (approximate)5×1018 cm−3. The deposition sequence and metal layer thicknesses were: Pt (50 nm), Ti (30 nm), Ge (90 nm) and Pd (45 nm). The contact microstructure remained uniform up to 550 °C and consisted of a continuous polycrystalline layer of GePd at the semiconductor surface, along with pockets of epitaxially grown Ge. Annealing at 550 °C resulted in the nucleation of a Ge-deficient phase, Ge8Pd21, at the GePd/GaAs interface, which protruded into the GaAs and deteriorated the uniformity of the contact. At higher annealing temperatures, the contact degraded rapidly due to inward diffusion of Ti and Pt and outward diffusion of As, leading to the formation of several binary and ternary phases. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368246
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  • 10
    Electronic Resource
    Electronic Resource
    Study on surface and domain structures of PbTiO3 crystals by atomic force microscopy (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6795-6799 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface morphology of flux-grown PbTiO3 crystals is examined by atomic force microscopy (AFM) at room temperature. Surface undulations due to a and c domains are observed on as-grown and heated crystals. The surface bending angle at 90° a-c domain walls is measured to be (3.58°±0.05°) in good agreement with the theoretical value, 3.6°. Footprints of ancient domains are found to be overlapped by surface undulations of the actual domain after polishing and heating process. Reciprocal 180° domains embedded in a and c domains are observed by both AFM and by polarizing optical microscopy on etched crystals. Details of the etched pattern are explored. Contrary to abrupt changes of height at 180° walls in c domains, only very small grooves are detected at 180° walls in a domains. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369011
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