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  • 2000-2004  (17)
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  • 1
    Electronic Resource
    Electronic Resource
    Comparative study on the effects of ion density and ion energy on diamond-like carbon deposited by electron cyclotron resonance chemical vapor deposition (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4830-4835 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond-like carbon films were deposited using electron cyclotron resonance (ECR) chemical vapor deposition incorporated with a screen grid under different dc bias voltages to compare the effect of ion density and ion energy on the film properties. Langmuir probe measurements and optical emission spectroscopy were used to characterize the ECR plasma, while the films were characterized using Raman and infrared (IR) spectroscopies, hardness, and optical gap measurements. The plasma measurements showed that the ion density, hydrogen atom density, and CH density decreased monotonously following increase in the dc bias voltage. Raman spectra and optical gap measurements indicate the films became more graphitic with lower content of sp3-hybridized carbon atoms as the dc bias voltage was increased. An increase in hydrogen content was found in films prepared at relatively high dc bias voltage, as indicated by IR measurements. Films deposited at −150 V exhibit maximum hardness. The results show the ion density has a stronger effect on the film deposition rate and hydrogen content, while the ion energy affects the film properties more predominantly by changing the bonding structure. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1359163
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  • 2
    Electronic Resource
    Electronic Resource
    Non-Fermi-liquid behaviour in La 4 Ru 6 O 19 (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 411 (2001), S. 669-671 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Understanding the complexities of electronic and magnetic ground states in solids is one of the main goals of solid-state physics. Transition-metal oxides have proved to be particularly fruitful in this regard, especially for those materials with the perovskite structure, where the special ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35079534
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  • 3
    Electronic Resource
    Electronic Resource
    Emergent excitations in a geometrically frustrated magnet (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 418 (2002), S. 856-858 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Frustrated systems are ubiquitous, and they are interesting because their behaviour is difficult to predict; frustration can lead to macroscopic degeneracies and qualitatively new states of matter. Magnetic systems offer good examples in the form of spin lattices, where all interactions between ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature00964
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  • 4
    Electronic Resource
    Electronic Resource
    Superconductivity in the non-oxide perovskite MgCNi 3 (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 411 (2001), S. 54-56 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The interplay of magnetic interactions, the dimensionality of the crystal structure and electronic correlations in producing superconductivity is one of the dominant themes in the study of the electronic properties of complex materials. Although magnetic interactions and two-dimensional ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35075014
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  • 5
    Electronic Resource
    Electronic Resource
    Gastric medullary carcinoma, a distinct entity associated with microsatellite instability-H, prominent intraepithelial lymphocytes and improved prognosis (2004)
    Oxford, UK : Blackwell Science Ltd
    Histopathology 45 (2004), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aims:  To determine the clinicopathological and molecular features of gastric medullary cancer.Methods and results:  Clinicopathological review and microsatellite instability (MSI) analysis were carried out on 17 gastric medullary and 64 non-medullary cancers. In addition to characteristic histopathology, gastric medullary cancers had certain prominent features: (i) the average survival time was longer in medullary and low-grade non-medullary cancers than in high-grade (P = 0.004); (ii) serosal involvement was less common in medullary cancers (29.4%, 5/17) than in non-medullary cancers (9.4%, 6/64) (P 〈 0.05) while pushing borders were more common in medullary cancers (70.6%, 12/17 versus 17.2%, 11/64, P = 0); (iii) the presence of intraepithelial lymphocytes (IELs) in medullary and non-medullary cancers was 2380/10 high-power field (HPF) and 147/10 HPF (P = 0), respectively. Both peritumoural infiltrating lymphocytes (pTIL) and a Crohn's-like reaction were more common in medullary cancers than in non-medullary (pTIL 35.3%, 6/17 versus 3.1%, 2/64; a Crohn's-like reaction 70.6%, 12/17 versus 32.8%, 21/64; P 〈 0.05); (iv) medullary and high-grade non-medullary cancers were more associated with reduced ECD expression in comparison with low-grade cancers (P 〈 0.05); (v) higher MSI-H (Bat26+) rate was observed in medullary cancers (41.2%, 7/17) than in non-medullary (1.6%, 1/64) (P = 0).Conclusions:  Gastric medullary cancer has distinct clinicopathological features and genetic alterations. Two subtypes of gastric medullary cancers, Bat26+ and Bat26–, might have prognostic implications, thus analysis of Bat26 may be of clinical value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2559.2004.01998.x
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  • 6
    Electronic Resource
    Electronic Resource
    Thickness dependence of density of gap states in diamond films studied using space-charge-limited current (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5747-5753 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural and electrical characteristics of chemical vapor deposited (CVD) diamond films have been studied as a function of film thickness. The samples comprise a set of codeposited, nominally undoped diamond films with average grain size on the growth surface increasing linearly with the film thickness. Raman scattering analysis reveals a decrease of nondiamond phase and intragrain defects with increasing film thickness. Temperature dependent dc conductivity results indicate that, as the film thickness increases, the Fermi level moves towards the valence band. There is a corresponding decrease in the density of states at the Fermi level, as deduced from the space-charge-limited current in the bulk of the samples. The spatial variation in the density of states through the material closely reflects the changes observed in the structural and electrical properties of the films. Such characteristic has the implication on the application of CVD diamond in the area of electronics. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1360222
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  • 7
    Electronic Resource
    Electronic Resource
    Conduction mechanism in molybdenum-containing diamond-like carbon deposited using electron cyclotron resonance chemical vapor deposition (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 4191-4195 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The conduction mechanism of molybdenum-containing (Mo) diamond-like carbon films deposited using electron cyclotron resonance chemical vapor deposition was investigated. It is found that there is a conductivity turning point at around 115 K, above which the conductivity is strongly temperature dependent. This indicates that two types of conduction mechanisms, thermal activation and tunneling coexist in the films, and they dominate the conduction behavior in the high and low temperature regimes, respectively. Within the temperature range investigated, the Poole–Frenkel effect is to be expected for thermal activation. However, due to the low concentration of Mo in the films, this effect was not observable. Tunneling is thought to occur between the Mo clusters or the sp2 clusters. A conductivity model, based on the thermal activation and tunneling, is proposed, and showed good agreement with the results obtained at low field. The conduction behavior at high field is also discussed and some possible mechanisms are proposed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1308102
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  • 8
    Electronic Resource
    Electronic Resource
    Enhanced magnetoresistance in Ag-doped granular La2/3Sr1/3MnO3 thin films prepared by dual-beam pulsed-laser deposition (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7428-7430 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article, we report our investigations on the doping effect metallic Ag on the intergrain magnetoresistance phenomenon. La2/3Sr1/3MnO3 (LSMO) thin films with Ag doping were prepared on (001) LaAlO3 at different substrate temperatures (Ts) by the dual-beam pulsed-laser deposition technique. Grown at Ts=750 °C, the films are perfectly epitaxial with their c axis perpendicular to the film surface. Ag dopant cannot substitute into the LSMO lattice, thus showing no obvious effect on the magnetotransport properties of the film, though it did impair the film in-plane epitaxy and improve the intergrain diffusion of the lattice atoms. However, grown at lower Ts(400 °C), the films are granular with c-axis texture. The Ag dopant exists at GBs and helps to increase the local Mn spin disorder at GBs and the phase interfaces, thus enhancing the eMR value by a factor of 2 compared with the undoped film. Experiment data also suggest that the transport mechanism underlying the Ag-doping enhanced eMR is spin-dependent scattering. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1362660
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  • 9
    Electronic Resource
    Electronic Resource
    Investigation of molybdenum-carbon films (Mo–C:H) deposited using an electron cyclotron resonance chemical vapor deposition system (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3699-3704 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have recently proposed a technique for depositing metal incorporated carbon films (Me–C:H) based on an electron cyclotron resonance chemical vapor deposition (ECR) process. This technique employs an ECR plasma derived from the excitation of source gases CH4 and Ar, together with two grids embedded within the chamber that serve as the source of the metal. It has been successfully applied for the deposition of tungsten–carbon films (W–C:H) which have been shown to exhibit a wide range of electrical, optical, and microstructural properties. These properties can be controlled through varying the deposition conditions such as the bias voltages at the grids and the substrate holder, and the flow ratio of CH4/Ar. In this work, we report on the growth and characterization of molybdenum–carbon (Mo–C:H) films deposited using the above technique incorporating two pure Mo grids. The effect of radio-frequency induced direct-current (dc) bias at the substrates was investigated. It was found that the resistivity of the films decreased by 9 orders of magnitude, and the optical gap decreased by more than 2 eV with increasing bias voltage from −38 to −130 V. The results suggest that the substrate dc bias has a crucial effect on the incorporation of Mo into the a-C:H films and the resulting microstructures, with larger bias voltages leading to an increase in the Mo fractions in the films. Concurrently, the hardness of the films was found to deteriorate from 22 to 10 GPa. The structures of these Mo–C:H films were characterized using x-ray diffraction and Raman scattering. Mo was found to exist in the forms of Mo and MoC and Mo2C. The experimental results are interpreted in terms of the effects of ion energy on the structure of the films having Mo clusters embedded within an amorphous carbon matrix. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288224
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of Fe doping on high field magnetoresistance and low field magnetoresistance at zero field in polycrystalline La0.7Sr0.3Mn1−xFexO3 (x=0–0.12) thin films (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7410-7412 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline La0.7Sr0.3Mn1−xFexO3 thin films, with x=0–0.12, have been prepared on (001)-Si substrates using pulsed laser deposition. The films consist of fine grains with an average size of 60–80 nm. For those films, the metal–insulator transition temperature, Tp, is much lower than the Curie temperature, TC. The high field magnetoresistance, HFMR, is nearly temperature independent for x〈0.08, whereas the extrapolated low field magnetoresistance at zero field, LFMR*, decreases rapidly with increasing temperature. Moreover, Fe doping significantly decreases LFMR* and enhances HFMR at low temperatures. We propose that for the Fe-doped films, both the reduced spin polarization of conduction electrons and the increased spin-flip scattering are responsible for the decrease of LFMR*, while the weakened ferromagnetic spin interaction at the grain boundaries is responsible for the enhanced HFMR. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1358344
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