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> Nanotech forum > Nanotech > Experiment idea: PASSING CURRENT THROUGH VORTEX CORES
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Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
Alexey
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Mon Apr 2 04:58:18 2007
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Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
Experiment: how to inject current into vortex cores and how to detect trapping-detrapping transitions in superconductors with columnar defects.
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| Created: Sat May 19 03:34:51 2007
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Alexey
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Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
A possible experiment might be as follows:
(1)take a superconducting plate (call it A), (2) deposit or grow a thing oxide on it, (3) deposit a superconducting film (B) and the oxidized plate A, (4) oxidize film B, (4) deposit another superconducting film C on top of B.
(The experiment can also be done with two plates or films for simplicity.)
Now one can measure I(V) curves of this three-layer system. If the voltage V<2delata, the current is zero (delta is the superconducting gap; here e=1). If a magnetic field is applied perpendicular to the A-B-C three layered sample, then vortices enter into layer B (as well as in A and C layers). One can expect that a current should no be above zero even in the range of voltages delta<V<2delate. This is due to the fact that electrons from a superconductor (say layer A) can tunnel into normal states present in the vortex core (vortex being in layer B). Alignment of vortices might even give a nonzero current at V<delta. In a sense vortices would act as thin “wires” carrying normal currents (note supercurrents can be made zero by making the oxide layer thick enough).
The experiment may be used to observe phase transitions in samples with holes or columnar defects. If some holes are present in the layer B (and other layers) then the current should be zero at V<2delata, even if vortices are present but all of them are trapped inside holes. Now, if by the effect of temperature or field, vortices exit the holes, the normal cores of vortices would contribute to an increase in the current.
This experiment should be done at low temperatures (to reduce the quasiparticle currents) and with high-quality tunnel junctions (to make sure that the subgap current is negligible).
The trapping-release transition of vortices was observed here for example:
“Role of edge superconducting states in trapping of multiquanta vortices by microholes. Application of the Bitter decoration technique,” A. Bezryadin B. Pannetier, J. Low Temp. Phys. 102, 73–94 (1996).
(link to the paper is here: http://research.physics.uiuc.edu/Bezryadin/Pubs/Bezryadin%20and%20Pannetier%20JLTP%201996.pdf)
(see fig.5)
In this paper the holes in the Nb film model columnar defects. Such experiment might even be possible with layered structures having actual columnar defects.
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| Created: Sat May 19 03:35:04 2007
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RP
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Sun Jun 3 04:00:34 2007
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RE: Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
this sabject has huge literature attached. the problem with CDs is that there is an ewasy way to de-pin a vortex by forming two kinks that then slide in oppisite directions. one really needs angular-dependent studies (see, e.g., "Origin Of the Irreversibility Line In Thin YBa2Cu3O7-d Films With and Without Columnar Defects", Phys. Rev. B 54 (21), 15530-15536 (1996)).
in either case, what do you want to accomplish (by passing current through the core)? Study de Gennes bound states? |
| Created: Sun Jun 3 20:27:10 2007
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Alexey
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RE: Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
Not necessarily I think. If one makes a thin film (thinner than ksi(T) for example), then vortices would not be able to form those kinks you are talking about. Is there any literature on the experimental study of current flowing through cores? I think it is not even clear whether it is possible. One might think that condensate will shunt the cure electrically and the current will go through the condensate. So there is a fundamental question here (unless somebody has answered it already): is it possible or not to confine electrical current in a vortex core? de Gennes bound states would be another interesting thing to study. For this purpose one needs to use thin films also to make these states resolvable.
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| Created: Sat Jun 9 18:34:53 2007
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RP
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RE: Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
| in your scenario, there will be no kinks. However, there will be BKT physics. In either case, tunneling to vortex core is a well-established field. There, current does flow through... |
| Created: Wed Jun 13 05:15:32 2007
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Alexey
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Mon Apr 2 04:58:18 2007
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RE: Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
| well-established field??? Can you give a single reference of a paper in which passing current through a vortex core was reported??? |
| Created: Thu Jun 21 22:15:10 2007
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RP
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Sun Jun 3 04:00:34 2007
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RE: Experiment idea: PASSING CURRENT THROUGH VORTEX CORES |
Wow - can't you use SciFinder?
e.g.,
PRB 40, 10778 (1989)
PRL 64, 2711 (1990)
Physica C 332, 44 (2000)
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| Created: Fri Jun 29 08:59:09 2007
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