Monday, January 14, 2013

Superconducting London Moment from Mechanics Condsiderations

So, this is cool!  I've been studying the London moment in superconductors for one of my research projects. It's an effect predicted by Fritz London.  When a superconductor is made to rotate, it generates a magnetic field parallel to its axis of rotation.  The magnetic field is termed the London moment.  London theorized its existence by considering the superconducting electrons to be a viscous fluid.

Here's the cool part. I came across an article in the American Journal of Physics where the author R. G. Rystephanick shows that the London moment can be derived simply by considering the assumption that when the superconductor spins, there should be no static force created by the Coriolis effect on the superconducting electrons.  This gives the following very simple derivation

1.  Aforementioned AJP article
Rystephanick R.G. (1976). Electromagnetic fields in rotating superconductors, American Journal of Physics, 44 (7) 647. DOI:

Picture of the Day:
From 1/14/13

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