A superconducting first near absolute zero

The first material to show superconductivity at its surface when it is not superconducting in its bulk form is reported online this week in Nature Nanotechnology. Superconductivity is the absence of resistance to electric current in a material that has been cooled below a certain temperature, and it was first observed 100 years ago. Masashi Kawasaki and colleagues deposited metal electrodes on a single crystal of potassium tantalate and then added a drop of liquid that can conduct electricity to make a device called an electric double-layer transistor. They find that the very high electric field produced by the transistor causes the surface of the potassium tantalate crystal to become superconducting at temperatures below 0.005 of a degree above absolute zero.Although this new material is not expected to have immediate applications, it may help researchers find other new superconductors.

doi: 10.1038/nnano.2011.78

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