Can extra electrons be added to a superconductor?

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Offline jeffreyH

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I am considering a superconductor having electrons somehow added to the conduction band. If this is an absurd question then my apologies in advance.

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Offline chiralSPO

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Re: Can extra electrons be added to a superconductor?
« Reply #1 on: 22/05/2016 16:29:52 »
My understanding is that metallic superconductors (supercooled mercury, copper etc.) can have some net charge and still behave as superconductors. I don't know how ceramic superconductors would fair, but I think you could probably add a few extra electrons into the conduction band... I'll look into it and think about it some more...

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Offline jeffreyH

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Re: Can extra electrons be added to a superconductor?
« Reply #2 on: 22/05/2016 16:34:42 »
My understanding is that metallic superconductors (supercooled mercury, copper etc.) can have some net charge and still behave as superconductors. I don't know how ceramic superconductors would fair, but I think you could probably add a few extra electrons into the conduction band... I'll look into it and think about it some more...

This question arose in regard to your paragraph in the electron/proton cloud thread so I would be interested in what you find.

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Offline chiralSPO

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Re: Can extra electrons be added to a superconductor?
« Reply #3 on: 22/05/2016 17:34:44 »
perhaps you could be more specific as to what you are proposing to do to a superconductor. I don't think you can add a significant number of electrons into the conduction band without dramatically changing the properties of the material. I can't imagine having any sort of significant gravitational effect...

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Offline jeffreyH

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Re: Can extra electrons be added to a superconductor?
« Reply #4 on: 22/05/2016 18:58:04 »
perhaps you could be more specific as to what you are proposing to do to a superconductor. I don't think you can add a significant number of electrons into the conduction band without dramatically changing the properties of the material. I can't imagine having any sort of significant gravitational effect...

I am not looking for a gravitational effect. A while back I was looking at the mass and charge discrepancy between electron and proton. It occurred to me that some new effect could be created by adding electrons to a superconductor. Don't ask me why it just occurred to me out of the blue. Call it a hunch.

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Offline jeffreyH

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Re: Can extra electrons be added to a superconductor?
« Reply #5 on: 22/05/2016 19:21:08 »
The only thing I found was on cuprates used as superconductors.

http://phys.org/news/2014-12-electron-key-high-temperature-superconductivity.html

Of signifigance is this.

"Normally, superconductors hate magnetism," says Grioni. "Either you have a good magnet or a good superconductor, but not both. Cuprates are very different and have really surprised everyone, because they are normally insulators and magnets, but they become
superconducting when a few extra electrons are added by gently tweaking its chemical composition."

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Offline chiralSPO

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Re: Can extra electrons be added to a superconductor?
« Reply #6 on: 01/06/2016 18:40:21 »
This question is addressed experimentally and theoretically in this article from 2013:
http://www.nature.com/nmat/journal/v12/n11/full/nmat3723.html

I don't think the article is publicly available without a substantial fee, but I have taken the liberty of providing a screenshot of the figure that addresses this question. There is apparently a fairly narrow sweet spot in terms of added electrons (substituting strontium for lanthanum), and once the material has too much strontium, the superconductivity is lost.