In memoriam: K Alex Muller, innovator in ceramic superconductors

By Dylan Loeb McClain

NEW YORK: It’s rare for a scientist to receive a Nobel Prize in Physics for discoveries made close to the age of 60, or for work done shortly before the prize is announced.

But K. Alex Müller, a Swiss physicist, was 59 when he made his breakthrough, and he had to wait only 16 months before he received his Nobel Prize, in 1987, sharing it with a colleague for discovering that some ceramics can be superconductors, opening up a world of scientific and practical possibilities.

Dr. Müller died on Jan. 9 at an assisted living facility in at 95, according to an announcement on Tuesday by IBM, where he had worked as a researcher.

The University of Zurich, where Dr. Müller was once a professor and where he maintained an office after retirement, said he died in Zurich.

A superconductor is a material, generally black in color, that is able to convey electricity without resistance; a current running through it will never dissipate. Superconductors have another useful property: They create powerful magnetic fields.

Superconductivity was discovered accidentally in 1911 by Heike Kamerlingh Onnes, a Dutch physicist, who received the Nobel Prize in 1913 for cooling a series of gases down to the point that they become liquids.

That temperature is usually near absolute zero, defined as minus 460 degrees Fahrenheit, or 0 Kelvin.

Dr. Kamerlingh Onnes made his discovery about superconductivity while cooling mercury to minus 452 degrees Fahrenheit (about 4 Kelvin). He later found the superconducting temperature of tin (minus 453 degrees Fahrenheit) and lead (minus 447 degrees).

In the decades that followed, scientists made incremental progress at discovering materials that became super-conductive at higher temperatures.

But by the late 1970s, no one had found anything that did so at a temperature higher than minus 424 degrees Fahrenheit, which made the use of superconductors impractical.

In the early 1980s, Dr. Müller was working at IBM Research in Zurich — a laboratory he had been associated with since 1963 — when he became interested in finding high-temperature superconductors. To work with him, he recruited J. Georg Bednorz, whom he had advised on his Ph.D. work at the Swiss Federal Institute of Technology.

They began testing strontium titanate, an oxide that is classified as a ceramic because it is neither metal nor organic. Dr. Müller had studied the properties of strontium titanate for 15 years and thought that it could be modified to be a high-temperature superconductor. He turned out to be wrong, but he and Dr. Bednorz learned some valuable lessons and set about creating and testing other ceramics.

A quantum leap forward came in early 1986, when they created lanthanum barium copper oxide, a ceramic that became super-conductive at about minus 400 degrees Fahrenheit. The publication of their results later that year ignited a frenzy in the scientific community as others raced to find ceramics that might be super-conductive at even higher temperatures.

Hugo Keller, a physics professor at the University of Zurich, described Dr. Müller and Dr. Bednorz’s research as a “breakthrough.” “Nobody expected to find superconductivity in such compounds,” he said. “Even more surprising was their high critical temperature.” The Royal Swedish Academy of Sciences, which awards the Nobels, promptly recognized the advance as well, bestowing the physics prize jointly on Dr. Muller and Dr. Bednorz in October 1987.