Karl Alexander Müller
1927–2023, Basel, Switzerland, Zurich, Switzerland
Swiss physicist who, with Georg Bednorz, discovered superconductivity above 35 K in copper-oxide ceramics, opening the era of high-temperature superconductors.
An IBM Zurich researcher known for work on perovskite ferroelectrics, Müller bet in 1983 — against the received wisdom that superconductivity topped out near 23 K — that strong electron-phonon coupling in polarizable oxides could raise Tc dramatically. With Bednorz he synthesized the lanthanum-barium-copper oxide that reached ~35 K in 1986. Their paper, initially doubted, triggered a worldwide scramble that within a year produced materials superconducting above liquid-nitrogen temperature.
Nobel-winning work
Müller shared the 1987 Nobel Prize for 'the discovery of superconductivity in ceramic materials'. Guided by his hypothesis that the Jahn-Teller-active Cu²⁺ ion in oxide perovskites would enhance pairing, he and Bednorz prepared La₂₋ₓBaₓCuO₄, whose resistance vanished below about 35 K — well above the 23.2 K record held since 1973 by Nb₃Ge.
The January 1986 discovery (published September) broke a seventy-year ceiling on Tc. Within months the YBCO compound exceeded 90 K, making liquid-nitrogen cooling practical and spawning the field of cuprate superconductivity, still not fully explained today.
Workplaces: IBM Zurich Research Laboratory, University of Zurich
Switzerland