Nichtlineare Eigenschaftenkoplanarer supraleitender Mikrowellenbauelemente aus YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ in kleinen Magnetfeldern
Nichtlineare Eigenschaftenkoplanarer supraleitender Mikrowellenbauelemente aus YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ in kleinen Magnetfeldern
Compared to normal conductors, superconductors exhibit extremely small microwavesurface resistances and, thus, provide a number of advantages for the use of thesematerials in microwave applications, e.g. mobile communication. For instance, as aconsequence of the small surface resistance very compact...
| Personal Name(s): | Lahl, Peter (Corresponding author) |
|---|---|
| Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
| Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2002
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| Physical Description: |
127 p. |
| Document Type: |
Report Book |
| Research Program: |
Addenda |
| Series Title: |
Berichte des Forschungszentrums Jülich
3923 |
| Link: |
OpenAccess OpenAccess |
| Publikationsportal JuSER |
|
Compared to normal conductors, superconductors exhibit extremely small microwavesurface resistances and, thus, provide a number of advantages for the use of thesematerials in microwave applications, e.g. mobile communication. For instance, as aconsequence of the small surface resistance very compact and smallsuperconducting microwave devices with even better performance could replacelarge and bulky normal conducting devices. However, the compactness of thesuperconducting devices automatically leads to high power densities in thesedevices. Since the rf surface resistance of superconductors is nonlinear the powerhandling capability is limited in these devices. This represents a serious limitation forthe use of superconductors in microwave applications. The examination and, ifpossible, explanation of this mechanism, that is responsible for the nonlinearities insuperconducting microwave devices has not been unambiguously identified up tonow.In this work, the nonlinear properties of high-T$_{c}$ superconducting microwave devicesare investigated and the mechanism that limits the power handling capability isderived from the experiment. For this purpose, additional to the rf electromagneticfield, dc magnetic fields are employed as a probe for the analysis of the localmaximum rf electromagnetic field. Coplanar microwave resonators which exhibit acharacteristic rf current density distribution are manufactured from YBa$_{2}$CU$_{3}$O$_{7-\sigma}$ thinfilms an sapphire and LaA103 substrates. It is shown that the behaviour of theseresonators in dc magnetic fields depends strongly an the vortex distribution in theresonator and, therefore, an the way the magnetic field is established. Theexperimental results are explained in terms of a model which consistently describesthe behaviour in magnetic fields and in zero field. The results are important for theunderstanding of the mechanism that limits the power handling capability as well asthey give a first insight into vortex matter (pinning and mobility) in rf fields.Furthermore, they represent the basis for improvements of the microwave propertiesof superconducting devices for applications, which is indicated in this work. |