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| Heater |
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Schematic of the heater assembly for pulsed laser deposition. |
| Principle of a Scanning Probe Microscope |
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A scanning probe microscope. The properties of the sample surface are detected by a probe. Probe or sample are scanned by a fine positionig device. With the coarse positioning system, the distance between sample is reduced until the interaction region is reached. |
| Fabrication of coated conductors - part 2 |
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Today's dip and spray coating technologies are rapidly advancing, so that in near future coated conductors may be produced with non-vacuum techniques. A Ca-doped cap-layer of superconductor additionally optimizes the grain boundaries and garantuees high values of the critical current density. |
| Fabrication of coated conductors - part 1 |
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For the RABiTS technology, which is one promising way to fabricate coated conductors, one needs biaxially textured substrates, which can easily be produced by appropriate rolling and heating metallic tapes (usually nickel alloys). |
| Selectively doping grain boundaries in coated conductors |
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This is the principle of a doping heterostructure on coated conductors. A Ca-doped toplayer on an undoped coated conductor offers enough Ca to diffuse along the grain boundaries and to optimize the grain boundary while leaving the bulk properties untouched. This way, the critical current density can be increased. |
| Substrate with elongated grains |
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If a superconductor consists of long grains, you will get grain boundaries with large grain boundary areas, across a high critical current may meander, although the critical current density might be low. |
| Cut through the UHV-goniometer |
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Cut through the four-axis UHV-goniometer, that was specifically designed and build for the use with the high-pressure RHEED system. |
| Cut through the ion-etching system |
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Cut through the ion-etching system designed by Andreas Schmehl |
| Cut through the sputtersystem |
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Cut through the sputter system designed by Andreas Schmehl |
| Illustration of atomically resolved friction microscopy |
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Illustration of atomically resolved friction microscopy. Frictional heat is dissipated by phonons within tip and sample. |
| Principle of our pi-SQUID |
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This sketch illustrates the principle of a pi-SQUID: on the substrate (gray) the superconductor YBCO (red) is grown. The blue and white lopes show the d-wave symmetry of YBCO. Both SQUID arms contain 45° grain boundaries, which cause a phase shift of pi due to their special design (see the different lope colors facing each other in the arms). Therefore a pi-SQUID is obtained. |
| Sketch of a YBCO bicrystal |
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The sketch shows a bicrystal of a high-Tc superconducting film (YBCO), fabricated by epitaxially depositing YBCO on a bicrystalline substrate. |
| Bicrystal sketch with d-wave lobes |
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The sketch shows a grain boundary in a high-Tc superconductor. The grain boundary leads to misorientation of the macroscopic wave function of the superconductor, which has a dx2-y2 symmetry. The grain boundary is an excellent Josephson junction. |
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