GLORIA

GEOMAR Library Ocean Research Information Access

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
    Optimization of annealing parameters for the growth of epitaxial Ba2YCu3O7−x films on LaAlO3(100) (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6353-6360 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The superconducting and structural properties of Ba2YCu3O7−x (BYCO) films on LaAlO3(100) substrates can be improved by carefully optimizing the post-deposition annealing parameters. Films are grown by co-deposition of BaF2, Y, and Cu in the correct stoichiometric ratio to within 1% of 2:1:3. Annealing parameters in an ex situ furnace, including the ambient, annealing temperature, oxidation temperature, and duration of anneals are systematically studied. Films are characterized for epitaxial quality (χmin), morphology, critical temperature (Tc), sharpness of the superconducting transition (ΔT), and critical current density (Jc). For example, beyond simply dissociating BaF2, the use of wet O2 appears to prevent the agglomeration of oxides during the initial heating process, and then act to thermodynamically stabilize the basic BYCO film structure at high temperatures after being formed. Comparisons are made with the best single-crystal BYCO structural and electrical data available. The optimized films have relatively smooth morphology with χmin〈3%, Tc〉90 K, ΔT〈0.5 K, and Jc〉106 A/cm2 in essentially zero magnetic field at 77 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346881
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Giant magnetoresistance in layered magnetic compounds (invited) (abstract) : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5332-5332 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Some stable compounds form in layered structures, in which magnetically ordered planes alternate with planes that are essentially nonmagnetic or disordered. SmMn2Ge2, for example, consists of planes of ferromagnetically aligned Mn2 separated by a SmGe2 structure (with the Sm moments disordered). Between 90 and 150 K, alternate Mn2 planes align antiferromagnetically, but can be rotated into overall ferromagnetic alignment by a moderate field (2–15 kOe). This is a classic metamagnetic behavior. A first-order structural phase transition accompanies the magnetic transition; it consists of a dilation of the c-axis lattice parameter and contraction of the a-axis lattice parameter with no discernable change in crystal symmetry. We have found that a 4%–8% change in the resistivity is associated with the magnetic transition, which may be related to band-structure effects as well as the elimination of the interlayer magnetic scattering channel. Since these are well-annealed, equilibrium compounds, they allow the study of this scattering channel in the limit of zero layer roughness (unlike thin film multilayers). The use of arc-grown single crystals allows us to measure the anisotropic response of the compounds: for example, the resistivity anisotropy of SmMn2 Ge2 is ρc/ρa∼25, and the AFM-FM transition is found to decrease ρc while it increases ρa. The study of this and similar layered structures serves as a complement to the study of artificial thin film magnetic multilayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353769
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Anomalous composition dependence of anisotropy in amorphous Tb-Fe and Ho-Fe (abstract) : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5466-5466 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic anisotropy Ku of magnetron cosputtered amorphous Tb-Fe has been found to drop precipitously when the composition is within several at. % of 22 at. % Tb, a composition which is the room-temperature compensation point. The samples showing this low value for Ku are magnetically saturated (fields up to 100 kOe were used) and torque curves have the expected uniaxial behavior. The unexpected decrease is correlated with a previous finding of anomalous, nonuniaxial anisotropy for films prepared with less than 22 at. % Tb when nonperpendicular incident angles are used for the deposition. We hypothesized that an undetected phase separation was occurring in these Fe-rich samples. The present study examines films prepared on rotating substrates, essentially eliminating the effect of incident angles. As previously predicted, with no incident angles the phase separation is unobservable by magnetic anisotropy, but presumably is still present and may account for the observed drop in Ku. Analogous results have been seen in amorphous Ho-Fe; the relevant composition is far from magnetic compensation, supporting the conclusion that the coincidence of compensation with the anomalies in Tb-Fe is accidental. This behavior of the anisotropy is inconsistent with simple models for the atomic structure and the source of Ku. The effect of deposition temperature will also be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348011
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Defect dominated charge transport in amorphous Ta2O5 thin films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 850-862 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ta2O5 is a candidate for use in metal–oxide–metal (MOM) capacitors in several areas of silicon device technology. Understanding and controlling leakage current is critical for successful implementation of this material. We have studied thermal and photoconductive charge transport processes in Ta2O5 MOM capacitors fabricated by anodization, reactive sputtering, and chemical vapor deposition. We find that the results from each of these three methods are similar if one compares films that have the same thickness and electrodes. Two types of leakage current are identified: (a) a transient current that charges the bulk states of the films and (b) a steady state activated process involving electron transport via a defect band. The transient process involves either tunneling conductivity into states near the Fermi energy or ion motion. The steady state process, seen most commonly in films 〈300 Å thick, is dominated by a large number of defects, ∼1019–1020 cm−3, located near the metal–oxide interfaces. The interior of thick Ta2O5 films has a substantially reduced number of defects. Modest heating (300–400 °C) of Ta2O5 in contact with a reactive metal electrode such as Al, Ti, or Ta results in interfacial reactions and the diffusion of defects across the thickness of the film. These experiments show that successful integration of Ta2O5 into semiconductor processing requires a better understanding of the impact of defects on the electrical characteristics and a better control of the metal–Ta2O5 interface. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373747
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Deposition and properties of NiFe2O4 thin films (abstract) : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6124-6124 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the properties of NiFe2O4 thin films prepared by laser ablation of a stoichiometric NiFe2O4 target. Textured polycrystalline films were obtained on a-SiO2 as well as on various substrates with Au, Ag, Pt, and MgF2 buffer layers. Epitaxially oriented films were obtained on MgO, (11¯02)-oriented Al2O3, (112¯0)-oriented Al2O3, Y-stabilized ZrO2 (YSZ), and SrTiO3, although the crystalline quality of the films varied. Contamination by diffusion from the substrate and strains induced by both lattice constant mismatch and differential thermal expansion degraded the magnetic properties of the films, and in some cases decreased the electrical resistivity as well. By choosing the right substrate (YSZ), temperature (600 °C), and PO2 (0.01 mT), we are able to prepare epitaxial films with bulk saturation magnetization (Ms=270 G) and fairly low anisotropy (K∼105 erg/cm3) as inferred by torque magnetometry. These films and bilayers are expected to be useful in a variety of fundamental investigations as well as having the potential for technological applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355481
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Magnetic properties of epitaxial ferrite multilayer films : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5923-5925 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated and studied the structure and magnetic properties of high quality single crystalline (Mn,Zn)Fe2O4, NiFe2O4, and CoFe2O4 films. Although (Mn,Zn)Fe2O4 and NiFe2O4 films grown directly on SrTiO3 and MgAl2O4 show mediocre structural and magnetic properties, these same films grown on SrTiO3 and MgAl2O4 buffered with CoCr2O4 or NiMn2O4 exhibit excellent crystallinity and bulk saturation magnetization values, thus indicating the importance of lattice match and structural similarity between the film and the underlying layer. X ray, Rutherford backscattering spectroscopy, atomic force microscopy, and transmission electron microscopy analysis provide a consistent picture of the structural properties of these ferrite films. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361844
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Interlayer exchange coupling in amorphous/crystalline NiFe2O4 thin-film bilayers : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5926-5928 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous/crystalline bilayers of NiFe2O4 exhibit interlayer magnetic exchange coupling, which results from an interaction between a spin-glass material and a ferrimagnetic material. The observed effect is reminiscent of the well-known exchange coupling effect between an antiferromagnet and a ferromagnet, which is widely used in applications where field biasing of thin magnetic films is desirable. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362173
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Temperature dependent exchange anisotropy in single-crystal ferrite thin films (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4989-4989 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystal bilayers of (magnetically soft) (Mn,Zn)Fe2O4 and (magnetically hard) CoFe2O4 can exhibit nearly ideal exchange anisotropy. This is directly related to the extremely high structural quality that can be achieved by epitaxial growth on appropriate substrates. For example, we use (110)-oriented MgAl2O4 substrates with 100 nm CoCr2O4 buffer layers. The paramagnetic buffer layer provides a close lattice match for the ferrites, and is annealed at about 1000 °C to provide excellent crystallinity. Subsequent growth of the ferrite bilayer is executed at 400 °C, which is high enough to permit growth of highly crystalline epitaxial films, yet low enough to avoid substantial intermixing at the interfaces. Measurements at elevated temperatures (290 K〈T〈1000 K) permit characterization of the exchange anisotropy in regimes of low and moderate crystal anisotropy in the soft layer, as well as directly revealing the blocking temperature and the portion of the overall magnetization contributed by each layer. The results provide additional evidence that the exchange coupling energy across the interface is comparable to that within each layer, and in that sense is nearly ideal. The detailed shapes of the M–H loops are found to be in semiquantitative agreement with micromagnetic theory. ©1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364962
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Critical currents and magnetization in c-axis textured Bi-Pb-Sr-Ca-Cu-O superconductors (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 868-870 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transport critical currents and magnetization behavior in c-axis textured Bi-Pb-Sr-Ca-Cu-O superconductor ribbons have been studied. The highly oriented layer structure was achieved by a combination processing of spray coating on silver foil, cold rolling, and partial melting. Transport Jc values as high as 2.3×105 A/cm2 at 4.2 K, H=8 T (H⊥ab) have been obtained. The high Jc at H≥5 T is maintained to temperatures near 20 K but it vanishes completely at or above ∼30 K, thus showing the limitation in useful, high-field operating temperatures for the Bi-system superconductors. A comparison of Jc (transport) and Jc (magnetization) indicates that the size scale of the circulating supercurrent loop in the Bean model nearly corresponds to the whole sample dimension rather than the orders-of-magnitude-smaller grain size. This demonstrates that the a-b grain boundaries in the melt-processed ribbons are not weakly coupled. The time decay of magnetization has also been studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104490
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Fabrication of thin-film superconductors by bulk processing (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1917-1919 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple processing technique for preparation of c-axis-oriented Bi-Pb-Sr-Ca-Cu-O thin films is reported. ∼3000-A(ring)-thick superconductor films on silver substrate have been obtained by heavy cold rolling and partial melt processing of the superconductor-silver composite structure. The films are highly textured due to the interface-induced, layer-like growth of the superconducting phase, and are essentially free of weak links. They exhibited Tc∼80 K and Jc (4.2 K) ∼104–105 A/cm2. This technique, which does not require epitaxial growth from single-crystal substrates, may be suitable for high-speed, low-cost production of large-area thin films, and points to other novel thin-film processing possibilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105047
    Location Call Number Limitation 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...