ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Interactions of YBa2Cu3O7−x thin films with alkaline earth fluoride substrates (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3194-3203 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Film-substrate interactions of YBa2Cu3O7−x (YBCO) thin films grown by pulsed laser deposition on alkaline earth fluoride substrates were investigated. X-ray photoelectron spectroscopy, atomic force microscopy, and x-ray-diffraction measurements showed that the quality of the film and amount of chemical reaction between film and substrate were dependent on the substrate material and deposition temperature. The reaction of YBCO films with CaF2 and MgF2 substrates forms BaF2 and calcium or magnesium oxide species. The reacted film is insulating and has a microscopically rough surface. No reaction was detected in films deposited on BaF2 and SrF2. Physical and thermodynamic properties which may explain the observed order of reactivity are examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354590
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Epitaxial relations between in situ superconducting YBa2Cu3O7−x thin films and BaTiO3/MgAl2O4/Si substrates (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1772-1776 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ superconducting YBa2Cu3O7−x films with Tc0 up to 87 K and Jc, 77 K up to 6×104 A/cm2 were prepared on Si substrates with MgAl2O4 and BaTiO3 double-buffer layers. The epitaxial relations between various layers were established by transmission electron microscopy. The MgAl2O4 layer is heavily faulted. The subsequent BaTiO3 layer stops most of the faults, provides a template for the YBa2Cu3O7−x growth, and partially screens off the stress due to different thermal expansion coefficients. The microstructure of the YBa2Cu3O7−x layer is very similar to that of the films deposited directly on SrTiO3, exhibiting a homogeneous heavily faulted single-crystal-like structure free from secondary phases and grain boundaries. The slight degradation of the transport properties is attributed to residual thermal stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346607
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Ex situ Ohmic contacts on thin film YBa2Cu3O7−x (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7927-7929 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on ex situ fabrication of gold contacts onto patterned YBa2Cu3O7−x films. Gold seed layers were blanket sputtered onto photoresist defined over the patterned films. In a second photo process, openings were aligned to the original pads and 8-μm-thick contacts were electroplated. The two layers of photoresist and sputtered gold were removed leaving defined contacts. We obtained specific contact resistance of 2.6×10−7 Ω cm2 on post-annealed samples at 79 K. Microwave filters with contacts showed 4.2 dB loss at 9 GHz and 77 K, while comparable filters in copper showed 18 dB loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347485
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Columnar defect induced phase transformation in epitaxial La0.7Ca0.3MnO3 films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4210-4215 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial La0.7Ca0.3MnO3 thin films on the SrTiO3(100) surface have been irradiated with 250 MeV Ag17+ ions at different nominal fluence values in the range of 5×1010–4×1011 ions/cm2, resulting in columnar defects. At low fluences these defects cause changes in material properties that are small and scale linearly with dosage. Above a threshold fluence value ∼3×1011 ions/cm2 dramatic changes are observed, including an order of magnitude increase in the resistivity and 50 K drop in the Curie temperature. Transmission electron microscopy measurements show that the changes are associated with a phase transformation of the undamaged region between the columnar defects. The transformed phase has a diffraction pattern very similar to that seen in charge-ordered La0.5Ca0.5MnO3. We propose that above a critical level of ion damage, strains caused by the presence of the columnar defects induce a charge-ordering phase transition that causes the observed dramatic changes in physical properties. We speculate that a conceptually similar surface-induced charge ordering may be responsible for the "dead layer" observed in very thin strained films, and the dramatic changes in optical properties induced by polishing, and that an impurity-induced charge ordering causes the extreme sensitivity of properties to lattice substitution. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373054
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Response to an electric field of Nd0.7Sr0.3MnO3 films in a MOSFET configuration (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4545-4545 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of an electric field on GMR oxide films was studied in a MOSFET configuration where the gate dielectric was a layer of SrTiO3 epitaxially grown on an underlying layer of the manganate which served as the source/drain. The response of the manganate channel was studied for different gate voltages. The following significant features were observed. The peak resistance temperature shifted to lower temperature for both polarities of the field. The resistance change varied quadratically with the field indicating the dominance of strain or polarization effects. In dynamical studies of the system using the gate voltage as an excitation the system showed anomalous slowing down near the peak of the resistivity. These results are understood on the basis of a stress effect on the film due to electro-elastic effects in the SrTiO3 layer, which introduces a tensile stress in the manganate layer upon the application of a gate voltage. The anomalous slowing down of the system near the ferromagnetic phase transition suggests a strong coupling between the spins, transport and structural distortions in the system. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361718
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Role of lattice distortions in the transport property of R0.7Me0.3MnO3 (R=Pr,Nd,La and Me=Ba,Sr,Ca) (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4552-4552 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: There are different models which to try to explain the transport properties of the manganese oxides in terms of magnetic polarons, Zener double exchange and Jahn-Teller distortions of the lattice which is temperature dependent. Using Rutherford backscattering techniques (2–3 MeV He ions) we are measuring the presence of lattice distortions by studying the angular scans in the channeling mode. The angular widths (FWHM) can be used to extract both dynamic and static displacements of the atoms from their equilibrium sites. The technique is extremely powerful in the sense that local uncorrected displacements as small as 0.01 A(ring) from the equilibrium position can be detected. The extraction of the physics from the data is relatively straight forward compared to other techniques such as XRD or neturon scattering. Using a variable temperature backscattering system at our center (one of three or four systems around the world) the angular width (FWHM) is found to exhibit a dramatic change with temperature increasing with decreasing temperature showing a possible correlation with both the transport and magnetic properties. The results suggest a decrease in the lattice disorder with reduced temperature far in excess of what one would predict on the basis of a simple Debye behavior. The reduction in the lattice disorder correlates very well with the resistance vs temperature dependence. A variety of manganese oxide epitaxial thin films grown by pulsed laser deposition have been studied and the data suggests a role for structural distortions in any mechanism to explain the transport properties of these materials. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361720
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Superparamagnetic behavior and giant magnetoresistance in oxygen deficient R0.67Sr0.33MnOz (R=Nd, Pr) epitaxial films (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4552-4552 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the magnetic and magnetotransport properties of oxygen deficient R0.67Sr0.33MnOz (R=Nd, Pr) films and have observed superparamagnetic behavior in these films. The superparamagnetism is indicated by (i) the increasing spread between zero field cooled (ZFC) and field cooled (FC) magnetization curves as temperature decreases, (ii) a sharp drop of the ZFC magnetization at low temperature, (iii) enhanced Curie–Weiss constant above the ferromagnetic temperature, and (iv) at low temperature a sharp drop of coercivity (Hc) with increasing temperature. These findings strongly suggest that all oxygen deficient manganites are magnetically inhomogeneous; i.e., ferromagnetic clusters exist. We estimate the spin cluster diameter to be 7–10 nm at low temperature (T〈30 K). We discuss a possible origin of the giant magnetoresistance effect based on the existence of spin clusters. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361545
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    dc electric field effect on the microwave properties of YBa2Cu3O7/SrTiO3 layered structures (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2937-2950 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a summary of our work on the dc electric field effect on the microwave properties of YBa2Cu3O7/SrTiO3 (YBCO/STO) layered structures. We briefly describe the fabrication of these layered structures, their structural and electrical properties related to the microwave response, and experimental methods to investigate dc electric field effects at microwave frequencies. Analysis of microwave measurements shows that dc electric field modulated changes in both the complex conductivity of YBCO layers and the dielectric properties of the STO layers contribute to the overall device response. At low temperatures (〈50 K) and large electric fields, good samples show linear gate-voltage modulation of microwave surface resistance and surface reactance attributable to field induced superconducting hole filling and depletion in the dominant YBCO layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357533
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Mechanisms of optical response in superconducting YBa2Cu3O7−δ thin films and grain-boundary weak links (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5829-5838 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical response of single grain-boundary weak links in superconducting YBCO thin films has been investigated. At temperatures well below the transition temperature, the grain boundary exhibits an optical response which is qualitatively different from transition edge response. Using a resistively shunted-junction model for the grain-boundary weak link, we find that the optical response below the transition temperature can be described by radiation induced thermal modulation of the critical currents of the weak links. The dependence on the bias current and the temperature distinguishes the weak-link optical response from the transition edge optical response. We discuss novel aspects of a potential radiation detector based on grain-boundary weak-link junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358396
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Superconducting and structural properties of Nd2−xCexCuO4−y thin films on perovskite and fluorite substrates (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2119-2124 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High quality epitaxial Nd2−xCexCuO4−y (NCCO) thin films were fabricated on various substrates by pulsed-laser deposition using N2O reactive gas. The similarities and dissimilarities of the superconducting and structural properties of NCCO films, on perovskite-type substrates such as LaAlO3, NdGaO3, and SrTiO3 and on a fluorite-type substrate of yttria-stabilized zirconia (YSZ), were investigated systematically as a function of film thickness by transport measurements and structural analysis. A remarkable reduction of Tc was observed when the film was thinner than a critical thickness, which strongly depends on the substrate. The critical thicknesses for which Tc is 80% of Tc max are 1200, 1000, 600, and 450 A(ring) for LaAlO3, NdGaO3, SrTiO3, and YSZ, respectively. YSZ turns out to be the best candidate for the growth of very thin NCCO films among the substrates studied. These results show a strong correlation between the strain and Tc in NCCO thin films and point the way to the fabrication of n-type superconducting electric field devices using ultrathin NCCO films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356318
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...