Dhe night of March 18, 1987 will be remembered forever by Karl Alexander Müller. At the time, several thousand physicists crowded the ballroom and hallways of the New York Hilton at the annual meeting of the American Physical Society – which has become known as the “Woodstock of Physics” – to hear his “historic” lecture. The Swiss physicist had to announce an incredible discovery that he and his colleague Georg Bednorz had made a year earlier. The two researchers had synthesized a ceramic oxygen compound at the IBM research laboratory in Rüschlikon near Zurich, which suddenly lost its electrical resistance below minus 238 degrees and mutated into a superconductor.
That was a sensation, as until then only metals were known that only became superconducting near absolute zero temperature (minus 273 degrees). A broad application of superconductivity seemed within reach. Now even superconductivity at room temperature seemed possible.
When Müller and Bednorz presented their high-temperature superconductor to the public for the first time shortly after its discovery in 1986, they were met with great skepticism. Because ceramic oxides were considered to be poor conductors of electricity. The last doubters were finally convinced when, a year later, in October 1987, Müller and Bednorz were awarded the Nobel Prize in Physics for their discovery. Incidentally, that was the first time that there was only a year between discovery and the Nobel Prize.
Waiting for wide application
The discovery made by the two researchers, which was preceded by years of trying out, discarding and remixing a wide variety of elements, triggered a hunt for ever warmer superconductors. , which is still ongoing. The record is still held by a mercury oxide ceramic discovered in 2000, which loses its electrical resistance below minus 135 degrees and can be cooled with cheaper liquid nitrogen instead of liquid helium.
Because high-temperature ceramic superconductors are difficult to process due to their brittleness, they have not yet found wide application. Occasionally, high-voltage cables are already being made from it. However, a material that carries electricity without resistance near the freezing point of water is still a dream. Alex Müller, who was born in Basel and received his doctorate from ETH Zurich in 1958, died in Zurich at the beginning of January at the age of 95, as has only just become known.