Superconductivity turns one hundred

By Marcus Wilson 03/05/2011

There’s a fair bit in the physics magazines at the moment on superconductivity.  has some interesting articles, for example this one by Ted Forgan and an interview with Frank Wilczek.

Superconductivity has its hundreth birthday this year. In 1911, in Leiden, Netherlands, Heike Onnes and Gilles Holst discovered that mercury lost its electrical resistance at 4.2 K.  This followed Onnes earlier development of a technique to liquify helium; he was honoured for this development with the 1913 Nobel Prize for Physics.

Since then, researchers have been interested in both how to use superconductors (e.g. how they interact with magnetic fields, as exemplified by the classroom levitation experiment), just why superconductors superconduct (from which we have learnt a lot about electrons and quantum mechanics) and how to make superconductors that are superconductive at higher temperatures. Room temperature superconductors would be an astonishing breakthrough, opening up vast possibilities, but they still remain a dream at the moment.

Experimentally, the stride forward that made superconductivity more than just a quirky bit of physics was the 1986-87 work in ceramics. A variety of compounds containing yttrium, barium, copper and oxygen (known as YBCO) are superconducting at temperatures above the boiling point of nitrogen (77 K). Liquid nitrogen is easy and cheap to get hold of, and so these superconductors are easily studied. Unfortunately, however, since then the record temperature has only inched upwards (standing at 138 K for atmospheric pressure, and that record has stood since1993) and it looks as if another quantum leap is required to get to room temperature.

But there are options other than YBCO that have been studied recently. There are plenty of researchers working on superconductors, for example in New Zealand we have a well respected. group at IRL, led by Buckley and Tallon. People have looked at organic materials and very recently iron compounds. Just perhaps, someday soon, someone will hit on something that pushes the superconducting temperature up another 100 Kelvin or so. That would really be Nobel Prize stuff.

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