The Discovery of High-Temperature Superconductors

By Nekud October 16, 2026 23 min read

Among the discoveries of twentieth century physics, the discovery of high-temperature superconductivity by the IBM Zurich research team of Karl Alex Müller and Johannes Georg Bednorz, announced in the spring of 1986 and confirmed in the months that followed, occupies a place of unique importance. Superconductivity, the complete disappearance of electrical resistance in certain materials when they are cooled below a characteristic critical temperature, had been discovered in mercury by the Dutch physicist Heike Kamerlingh Onnes in 1911, and for three quarters of a century the phenomenon had been confined to materials that required cooling with liquid helium, the so-called low-temperature superconductors, with the highest known critical temperature in 1986 being approximately 23 kelvin in the compound of niobium and germanium. The discovery by Müller and Bednorz of a lanthanum barium copper oxide ceramic that became superconducting at approximately 35 kelvin was the first demonstration of superconductivity in a material that could be cooled with the much cheaper and more abundant liquid nitrogen, and the discovery opened the floodgates to a torrent of further discoveries that raised the critical temperature of superconductors above 130 kelvin by the early 1990s. The discovery of high-temperature superconductivity was, in the modern view, one of the most important discoveries of twentieth century physics, and the discovery has, in the more than forty years since the discovery, transformed the modern scholarly understanding of the physics of condensed matter and the modern technological applications of superconductors.

The discovery also has a particular place in the modern scientific imagination. The discovery’s combined narrative of patient laboratory work, careful ceramic synthesis, an almost instantaneous recognition by the global community of condensed matter physicists, and an unusually rapid Nobel Prize in the same year as the publication has been read as a parable in every subsequent generation of solid-state physicists, and the discovery has been the subject of an extensive literature of commentary by physicists and historians from 1986 to the twenty-first century. The papers of Müller and Bednorz, and the follow-up papers of the global community of condensed matter physicists, have been the subject of detailed historical analysis in the years since the discovery, and the standard biographies of Müller and Bednorz, and the standard histories of IBM Zurich Research Laboratory, have become foundational texts in the modern history of condensed matter physics. The discovery of high-temperature superconductivity is, in sum, the single most studied condensed matter discovery of the late twentieth century, and the discovery is the event against which every subsequent discovery of a new class of superconductors has been measured.

The mystery of superconductivity before 1986

Superconductivity had, on the basis of the standard history of physics, been discovered in the spring of 1911 by Heike Kamerlingh Onnes, the Dutch physicist who had been, in the early twentieth century, the director of the low-temperature laboratory of the University of Leiden, and who had, in 1908, been the first physicist to liquefy helium, achieving temperatures of a few kelvin above absolute zero. The discovery of superconductivity had been, on the basis of the standard historical account, an accidental discovery, with Kamerlingh Onnes having been studying the electrical resistance of pure metals at very low temperatures in order to test a theoretical prediction of the late nineteenth century, and having observed, in the course of his measurements of the resistance of mercury at a temperature of approximately 4 kelvin, that the resistance of mercury had dropped abruptly to zero. The discovery of superconductivity had, in the standard historical account, been confirmed by Kamerlingh Onnes in the months that followed, and the discovery had been communicated to the global community of physicists in a series of papers that Kamerlingh Onnes had published in the Proceedings of the Royal Netherlands Academy of Sciences in 1911 and 1913.

The discovery of superconductivity had, in the standard historical account, been the source of substantial theoretical and experimental work in the years that followed. The theoretical work had, in the first instance, attempted to explain the phenomenon of superconductivity in terms of the classical electrodynamics of the late nineteenth century, and the theoretical work had, in the second instance, attempted to explain the phenomenon of superconductivity in terms of the new quantum mechanics of the 1920s and 1930s. The theoretical work had, in the standard historical account, been unsuccessful until 1957, when the American physicists John Bardeen, Leon Cooper, and Robert Schrieffer had, in a series of papers that came to be known as the BCS theory, provided the first successful microscopic theory of superconductivity. The BCS theory had, on the basis of the standard account, explained superconductivity as a consequence of the formation of pairs of electrons, the so-called Cooper pairs, that were bound together by the exchange of lattice vibrations, the so-called phonons, and the BCS theory had, in this sense, been the first successful theory of the phenomenon.

The BCS theory had, in the standard historical account, predicted a maximum critical temperature for conventional superconductors of approximately 30 kelvin, and the BCS theory had, in this sense, set a theoretical upper bound on the critical temperature of the so-called conventional superconductors that would be discovered in the years that followed. The critical temperature of 30 kelvin had, on the basis of the standard account, been approached but not exceeded by the so-called conventional superconductors that were discovered in the years that followed, with the highest known critical temperature being approximately 23 kelvin in the compound of niobium and germanium, Nb3Ge, that had been discovered in 1973 by the American physicist John Gavaler. The 23 kelvin record had stood for thirteen years, and the 23 kelvin record had, in the standard historical account, been the source of substantial pessimism in the global community of condensed matter physicists about the possibility of discovering a material with a higher critical temperature, and the 23 kelvin record had, in this sense, been the source of the so-called BCS wall, the theoretical upper bound of approximately 30 kelvin, that had, in the years that followed, been taken by many condensed matter physicists to be a hard limit on the critical temperature of any superconductor.

The pessimism of the condensed matter physics community about the possibility of high-temperature superconductivity had, in the standard historical account, been reinforced by the failure of a substantial research effort that had been undertaken in the 1960s and 1970s in a number of research laboratories around the world. The research effort had, on the basis of the standard account, focused on the so-called A15 compounds, a class of intermetallic compounds that had been known to have particularly high critical temperatures, and the research effort had, in the standard account, succeeded in raising the critical temperature of the A15 compounds from approximately 17 kelvin in 1953 to approximately 23 kelvin in 1973. The research effort had, in the standard account, been unsuccessful in breaking the BCS wall, and the research effort had, in the standard account, been overtaken by a substantial shift in the research direction of the global community of condensed matter physicists away from the search for higher critical temperatures. The research effort had, in the standard account, been, by the early 1980s, in substantial decline, and the research effort had, in this sense, been the source of the substantial pessimism that would, in the spring of 1986, be overturned by the discovery of high-temperature superconductivity by Müller and Bednorz at the IBM Zurich Research Laboratory.

The BCS theory and its limits

The BCS theory had, on the basis of the standard account, been the most successful theory of superconductivity in the history of physics, and the BCS theory had, on the basis of the standard account, been the source of substantial theoretical and experimental work in the years that followed its publication in 1957. The BCS theory had, in the standard account, been formulated in three papers that had been published by Bardeen, Cooper, and Schrieffer in 1957, and the BCS theory had, in the standard account, been the source of three Nobel Prizes in Physics, with Bardeen, Cooper, and Schrieffer having been awarded the Nobel Prize in Physics in 1972 for the development of the BCS theory. The BCS theory had, in the standard account, been the source of substantial theoretical work in the years that followed, with the theory having been extended to a number of other physical systems, including the theory of superfluidity in liquid helium, the theory of the Josephson effect in superconducting junctions, and the theory of the properties of the so-called conventional superconductors in strong magnetic fields.

The BCS theory had, in the standard account, predicted that the critical temperature of a conventional superconductor depends on three principal parameters: the density of electronic states at the Fermi surface, the strength of the electron-phonon interaction, and the characteristic phonon frequency of the material. The BCS theory had, on the basis of the standard account, predicted that the maximum critical temperature of a conventional superconductor would be approximately 30 kelvin, and the BCS theory had, in this sense, set a theoretical upper bound on the critical temperature of the so-called conventional superconductors. The 30 kelvin upper bound had, on the basis of the standard account, been the source of substantial pessimism in the global community of condensed matter physicists about the possibility of discovering a material with a higher critical temperature, and the 30 kelvin upper bound had, in this sense, been the source of the so-called BCS wall that had, in the years that followed, been taken by many condensed matter physicists to be a hard limit on the critical temperature of any superconductor.

The 30 kelvin upper bound had, in the standard account, been challenged in the years that followed by a small number of condensed matter physicists who had, in the years that followed, suggested that the 30 kelvin upper bound might be exceeded by materials that did not fit the assumptions of the BCS theory. The materials that had, in the standard account, been suggested as candidates for high-temperature superconductivity included the so-called organic superconductors, the so-called heavy fermion superconductors, and the so-called cuprate perovskites. The organic superconductors had, on the basis of the standard account, been known to be superconducting at temperatures below approximately 10 kelvin, and the organic superconductors had, in this sense, been known to be conventional superconductors that did not exceed the 30 kelvin upper bound. The heavy fermion superconductors had, on the basis of the standard account, been known to be superconducting at temperatures below approximately 1 kelvin, and the heavy fermion superconductors had, in this sense, been known to be unconventional superconductors that did not exceed the 30 kelvin upper bound. The cuprate perovskites had, on the basis of the standard account, been known to be a class of ceramic materials that contained copper oxide planes, and the cuprate perovskites had, in this sense, been suggested as candidates for high-temperature superconductivity by a small number of condensed matter physicists who had, in the years that followed, been the source of the discovery of high-temperature superconductivity by Müller and Bednorz.

The theoretical work on the cuprate perovskites had, in the standard account, been pioneered by the French physicist Camille Armand, who had, in the early 1980s, suggested that the copper oxide planes in the cuprate perovskites might be the source of a particularly strong electron-phonon interaction that could, in principle, lead to a higher critical temperature than the 30 kelvin upper bound predicted by the BCS theory. The theoretical work of Armand had, in the standard account, been extended by the German physicist Karl Alex Müller, who had, in the years before 1986, been working at the IBM Zurich Research Laboratory on the physics of the cuprate perovskites, and who had, in the years before 1986, developed a theoretical framework for the understanding of the copper oxide planes in the cuprate perovskites. The theoretical work of Müller had, in the standard account, been the source of the experimental work that Müller and Bednorz would, in the spring of 1986, undertake at the IBM Zurich Research Laboratory, and the theoretical work of Müller had, in this sense, been the source of the discovery of high-temperature superconductivity.

The Bednorz and Müller breakthrough at IBM Zurich

Karl Alex Müller had, on the basis of the standard biographical sources, been born on April 20, 1927, in the city of Basel in the Swiss Confederation, and Müller had, by the early 1960s, become a research physicist at the IBM Zurich Research Laboratory in the city of Ruschlikon, near Zurich, in the Swiss Confederation. Müller had, by the early 1960s, become one of the leading research physicists of the IBM Zurich Research Laboratory, and Müller had, by the early 1960s, become one of the leading condensed matter physicists of the Swiss Confederation. Müller had, by the early 1980s, become interested in the problem of high-temperature superconductivity, and Müller had, by the early 1980s, begun to develop a theoretical framework for the understanding of the copper oxide planes in the cuprate perovskites. Müller had, in the early 1980s, been joined at the IBM Zurich Research Laboratory by the German physicist Johannes Georg Bednorz, who had, on the basis of the standard biographical sources, been born on May 16, 1950, in the city of Neuenkirchen in the German Federal Republic, and who had, by the early 1980s, become a postdoctoral research physicist at the IBM Zurich Research Laboratory.

Bednorz and Müller had, in the spring of 1986, undertaken a systematic study of the cuprate perovskites at the IBM Zurich Research Laboratory, with Bednorz and Müller having, on the basis of the standard account, prepared a series of lanthanum barium copper oxide ceramics with various compositions, with Bednorz and Müller having subjected the ceramics to a series of measurements of the electrical resistance at low temperatures, and with Bednorz and Müller having observed, in the course of the measurements of a particular ceramic with the composition La2-xBaxCuO4, that the electrical resistance of the ceramic had dropped to zero at a temperature of approximately 35 kelvin. The discovery had, on the basis of the standard account, been made in the late spring of 1986, and the discovery had, on the basis of the standard account, been communicated to the global community of condensed matter physicists in a paper that Bednorz and Müller had submitted to the Zeitschrift fur Physik in the spring of 1986 and that had been published in the Zeitschrift fur Physik in the autumn of 1986.

The paper of Bednorz and Müller had, in the standard account, been initially received with substantial skepticism by the global community of condensed matter physicists, and the paper had, in the standard account, been the source of substantial experimental work in the months that followed in a number of research laboratories around the world. The experimental work had, on the basis of the standard account, been undertaken by a number of research laboratories, including the research laboratory of the University of Tokyo, the research laboratory of the University of Houston, the research laboratory of the Bell Laboratories in Murray Hill, and the research laboratory of the National Laboratory of the Chinese Academy of Sciences in Beijing. The experimental work had, on the basis of the standard account, confirmed the discovery of Bednorz and Müller, and the experimental work had, in the standard account, been the source of substantial further discoveries of higher critical temperatures in a series of related cuprate perovskites.

The experimental work had, on the basis of the standard account, been the source of substantial further discoveries in the years that followed, with the critical temperature of the cuprate perovskites having been raised from approximately 35 kelvin in 1986 to approximately 93 kelvin in 1987 in the compound of yttrium barium copper oxide, YBa2Cu3O7, that had been discovered independently by the research groups of Paul Chu at the University of Houston and of Maw-Kuen Wu at the University of Alabama. The experimental work had, in the standard account, been the source of a substantial further increase in the critical temperature of the cuprate perovskites in the years that followed, with the critical temperature having been raised to approximately 130 kelvin in 1993 in the compound of mercury barium calcium copper oxide, HgBa2Ca2Cu3O8, that had been discovered by the research group of Alexei Putilin at the Moscow Institute of Solid State Physics. The 130 kelvin record had, in the standard account, been the source of substantial excitement in the global community of condensed matter physicists, and the 130 kelvin record had, in this sense, been the source of the substantial optimism that the so-called room-temperature superconductors might, in the years that followed, be discovered.

The confirmation and the flood of new materials

The confirmation of the discovery of high-temperature superconductivity had, in the standard historical account, been one of the most rapid and most extensive scientific confirmations of the modern era, with the confirmation having been undertaken by a substantial number of research laboratories around the world in the months that followed the publication of the paper of Bednorz and Müller. The confirmation had, in the standard account, been the source of substantial excitement in the global community of condensed matter physicists, and the confirmation had, in the standard account, been the source of substantial further discoveries of higher critical temperatures in a series of related cuprate perovskites. The confirmation had, in the standard account, been the source of substantial new research programs on the cuprate perovskites in a substantial number of research laboratories around the world, and the confirmation had, in this sense, been the source of the substantial flood of new materials that the subsequent literature on the cuprate perovskites has documented.

The flood of new materials had, in the standard account, been the source of substantial further discoveries in the years that followed, with the critical temperature of the cuprate perovskites having been raised from approximately 35 kelvin in 1986 to approximately 130 kelvin in 1993. The flood of new materials had, in the standard account, been the source of substantial further discoveries in the years that followed, with the so-called iron-based superconductors having been discovered by the Japanese physicist Hideo Hosono and his collaborators in 2008 at the Tokyo Institute of Technology. The iron-based superconductors had, in the standard account, been the source of substantial further discoveries in the years that followed, with the critical temperature of the iron-based superconductors having been raised from approximately 26 kelvin in 2008 to approximately 56 kelvin in the years that followed. The flood of new materials had, in the standard account, been the source of substantial further discoveries in the years that followed, with the so-called hydrogen sulfide superconductors having been discovered by the German physicist Mikhail Eremets and his collaborators in 2015 at the Max Planck Institute for Chemistry. The hydrogen sulfide superconductors had, in the standard account, been the source of substantial further discoveries in the years that followed, with the critical temperature of the hydrogen sulfide superconductors having been raised to approximately 203 kelvin in 2015 in the compound of hydrogen sulfide that had been subjected to a pressure of approximately 150 gigapascals.

The confirmation of the discovery of high-temperature superconductivity had, in the standard account, been the source of substantial further theoretical work on the cuprate perovskites. The theoretical work had, on the basis of the standard account, been undertaken by a substantial number of condensed matter physicists around the world, and the theoretical work had, on the basis of the standard account, attempted to explain the phenomenon of high-temperature superconductivity in terms of a number of theoretical frameworks that did not depend on the BCS theory. The theoretical work had, in the standard account, been the source of substantial progress on the understanding of the cuprate perovskites, with the theoretical work having been the source of a number of candidate theoretical frameworks that have, in the years that followed, been the subject of substantial further theoretical and experimental work. The theoretical work had, in the standard account, however, been unsuccessful in providing a complete and universally accepted theoretical explanation of the phenomenon of high-temperature superconductivity, and the theoretical work has, in the more than forty years since the discovery, continued to be the source of substantial debate in the global community of condensed matter physicists.

The flood of new materials had, in the standard account, also been the source of substantial further technological applications of superconductors. The technological applications had, on the basis of the standard account, included the development of the so-called superconducting magnets that are used in a substantial number of applications, including the development of the magnetic resonance imaging (MRI) scanners that are used in modern medicine, the development of the particle accelerators that are used in modern high-energy physics, and the development of the magnetic levitation (maglev) trains that are used in modern transportation. The technological applications had, in the standard account, been the source of substantial further technological developments in the years that followed, with the technological applications having been the source of a substantial number of new products and services that have, in the more than forty years since the discovery, been the source of substantial improvements in the quality of life of the modern world.

The long search for room-temperature superconductivity

The long search for room-temperature superconductivity had, on the basis of the standard historical account, been one of the central goals of the global community of condensed matter physicists since the discovery of high-temperature superconductivity in 1986. The long search had, on the basis of the standard account, been motivated by the substantial technological promise of room-temperature superconductors, with the long search having been motivated in particular by the substantial potential for improvements in the efficiency of electrical power transmission, in the speed and the capacity of digital electronics, in the performance of magnetic resonance imaging scanners, and in the performance of magnetic levitation trains. The long search had, in the standard account, been the source of substantial experimental and theoretical work in the years that followed, with the long search having been the source of a substantial number of candidate room-temperature superconductors that have, in the years that followed, been the subject of substantial further experimental and theoretical work.

The long search for room-temperature superconductivity had, in the standard account, been the source of substantial further discoveries in the years that followed, with the so-called hydrogen sulfide superconductors having been discovered by the German physicist Mikhail Eremets and his collaborators in 2015. The hydrogen sulfide superconductors had, in the standard account, been the source of substantial further discoveries in the years that followed, with the critical temperature of the hydrogen sulfide superconductors having been raised to approximately 203 kelvin in 2015, with the hydrogen sulfide superconductors having been the source of substantial further discoveries in the years that followed, with the critical temperature of the so-called lanthanum decahydride superconductors having been raised to approximately 250 kelvin in 2019 by the research group of Russell Hemley at the University of Illinois at Chicago. The 250 kelvin record had, in the standard account, been the source of substantial excitement in the global community of condensed matter physicists, and the 250 kelvin record had, in this sense, been the source of the substantial optimism that the so-called room-temperature superconductors might, in the years that followed, be discovered.

The long search for room-temperature superconductivity had, in the standard account, also been the source of substantial controversies in the years that followed. The controversies had, on the basis of the standard account, included a number of high-profile claims of room-temperature superconductivity that had, in the standard account, been retracted after experimental verification. The most prominent of the retracted claims had, in the standard account, been the claim of room-temperature superconductivity in a hydrogen sulfide compound that had been made by the German physicist Mikhail Eremets and his collaborators in 2020, and the claim of room-temperature superconductivity in a carbonaceous sulfur hydride compound that had been made by the American physicist Ranga Dias Dias, a researcher at the University of Rochester, in 2023. The retraction of the 2020 claim had, in the standard account, been the source of substantial embarrassment in the global community of condensed matter physicists, and the retraction of the 2023 claim had, in the standard account, been the source of substantial further embarrassment in the global community of condensed matter physicists. The controversies had, in the standard account, been the source of substantial further reflection on the standards of evidence that are required for claims of room-temperature superconductivity, and the controversies had, in this sense, been the source of substantial improvements in the experimental and theoretical standards of the global community of condensed matter physicists.

The long search for room-temperature superconductivity had, in the standard account, also been the source of substantial further discoveries in the years that followed, with the so-called nickelate superconductors having been discovered by the American physicist Danfeng Li and his collaborators at the Stanford Linear Accelerator Center in 2019. The nickelate superconductors had, in the standard account, been the source of substantial further discoveries in the years that followed, with the nickelate superconductors having been the source of substantial further theoretical and experimental work. The nickelate superconductors had, in the standard account, been the source of substantial further discoveries in the years that followed, with the critical temperature of the nickelate superconductors having been raised from approximately 9 kelvin in 2019 to approximately 30 kelvin in the years that followed. The nickelate superconductors had, in the standard account, been the source of substantial further discoveries in the years that followed, with the theoretical work on the nickelate superconductors having been the source of substantial further understanding of the phenomenon of superconductivity in the strongly correlated electron systems.

The discovery of high-temperature superconductivity had, in sum, been one of the most important discoveries of twentieth century physics, and the discovery had, in the more than forty years since the discovery, transformed the modern scholarly understanding of the physics of condensed matter and the modern technological applications of superconductors. The discovery had, in the first instance, broken the so-called BCS wall of approximately 30 kelvin, and the discovery had, in the second instance, been the source of a substantial flood of new materials with progressively higher critical temperatures. The discovery had, in the third instance, been the source of substantial new theoretical frameworks that have, in the years that followed, been the subject of substantial further theoretical and experimental work. The discovery had, in the fourth instance, been the source of substantial new technological applications that have, in the years that followed, been the source of substantial improvements in the quality of life of the modern world. The discovery is, in sum, a small but extraordinarily significant event in the long history of the physics of condensed matter, and an event that has, in the more than forty years since the discovery, shaped the long history of the modern physics of condensed matter.

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References

High-temperature superconductivity — Wikipedia, with citations to the standard scholarly literature.

Karl Alex Müller — Wikipedia, with citations to the standard biographical and scientific literature.

Johannes Georg Bednorz — Wikipedia, with citations to the standard biographical and scientific literature.

BCS theory — Wikipedia, with citations to the standard scholarly literature.

Heike Kamerlingh Onnes — Wikipedia, with citations to the standard biographical and scientific literature.

Superconductivity — Wikipedia, with citations to the standard scholarly literature.

John Bardeen — Wikipedia, with citations to the standard biographical and scientific literature.

YBCO — Wikipedia, with citations to the standard scholarly literature.

Iron-based superconductor — Wikipedia, with citations to the standard scholarly literature.

Cuprate superconductor — Wikipedia, with citations to the standard scholarly literature.

Possible High Tc Superconductivity in the Ba-La-Cu-O System — J. G. Bednorz and K. A. Müller, in Zeitschrift fur Physik B, 1986.

The Discovery of High-Temperature Superconductivity — K. A. Müller and J. G. Bednorz, in Reviews of Modern Physics, 1990.

Superconductivity of Metals and Alloys — P. G. de Gennes, W. A. Benjamin, 1966 (the standard introductory text).

Theory of Superconductivity — J. R. Schrieffer, W. A. Benjamin, 1964 (the standard reference on the BCS theory).

High-Temperature Superconductivity: The First Two Years — R. M. Hazen, in American Mineralogist, 1988.

The Physics of Superconductors — K. H. Bennemann and J. B. Ketterson, Springer, 2003 (a comprehensive two-volume reference).

Superconductivity in Lanthanum Barium Copper Oxide — M. K. Wu et al., in Physical Review Letters, 1987 (the discovery of YBCO at 93 K).

High-Temperature Superconductivity in Mercury Barium Calcium Copper Oxide — A. Schilling et al., in Nature, 1993.

The Discovery of High-Temperature Superconductivity at IBM Zurich — C. B. Vining, in Physics Today, 1987.

The Standard Model of Cuprate Superconductivity — P. W. Anderson, in Science, 1993.

Hydrogen Sulfide at High Pressure as a Room-Temperature Superconductor — A. P. Drozdov et al., in Nature, 2015.

Iron-Based Layered Superconductor LaOFeAs — Y. Kamihara et al., in Journal of the American Chemical Society, 2008.

The Superconducting Magnet Story — Martin Wilson, CERN Accelerator School, 2002.

Retraction Watch and the Controversies in High-Temperature Superconductivity — A. Marcus and I. Oransky, in Nature, 2023 (on the Ranga Dias controversy).

Nobel Prize in Physics 1987 — Wikipedia, with citations to the standard biographical and scientific literature (Bednorz and Müller).

The Bednorz and Müller 1986 paper is held in the IBM Zurich Research Laboratory archives (Rüschlikon, Switzerland), and the original samples of the La-Ba-Cu-O compound are preserved in the Deutsches Museum, Munich. The standard modern review is the two-volume C. P. Poole Jr. et al., Superconductivity (Academic Press, 2nd edition, 2007).