The Search for Room Temperature Superconductors

By Nekud October 16, 2026 22 min read

Among the scientific holy grails of the modern era, the search for a room-temperature superconductor, a material that conducts electricity with zero resistance at ordinary ambient temperatures, occupies a place of unique importance. The search had, on the basis of the standard historical account, begun in the years following the discovery of superconductivity by the Dutch physicist Heike Kamerlingh Onnes in 1911, and the search has, in the more than one hundred years since the discovery, motivated an extraordinary range of theoretical and experimental work in the modern community of condensed matter physicists. The search had, on the basis of the standard historical account, been transformed by the discovery of high-temperature superconductivity by the IBM Zurich research team of Karl Alex Müller and Johannes Georg Bednorz in 1986, and the search has, in the years that followed, been the source of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of superconductors. The search for room-temperature superconductivity is, in the modern view, one of the most important research efforts of the modern community of condensed matter physicists, and the search has, in the more than one hundred years since the formulation of the search, transformed the modern scholarly understanding of the potential applications of superconductors.

The search also has a particular place in the modern scientific imagination. The search’s combined narrative of patient laboratory work, careful ceramic synthesis, high-pressure diamond anvil cell experiments, and an unusually rapid publication-and-retraction cycle of the most striking recent claim has been read as a parable in every subsequent generation of condensed matter physicists, and the search has been the subject of an extensive literature of commentary by physicists and historians from 1986 to the twenty-first century. The papers of the global community of condensed matter physicists, and the press releases of the various national laboratories that have been involved in the search, have been the subject of detailed historical analysis in the years since the search began, and the standard biographies of the principal architects of the search have become foundational texts in the modern history of condensed matter physics. The search for room-temperature superconductivity is, in sum, the single most studied research effort in the modern community of condensed matter physicists, and the search is the effort against which every subsequent research effort in the modern community of condensed matter physicists has been measured.

The BCS wall and the goal of room-temperature superconductivity

The BCS wall, the theoretical upper bound on the critical temperature of the so-called conventional superconductors that had been predicted by the BCS theory of superconductivity in 1957, had, on the basis of the standard historical account, set the original theoretical framework for the search for room-temperature superconductivity. The BCS wall 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 wall 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 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 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 wall had, on the basis of the standard account, however, also been the source of substantial theoretical work in the years that followed, with the BCS wall having been the source of the substantial theoretical work that would, in the years that followed, lead to the development of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of the so-called unconventional superconductors. The BCS wall 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, including the cuprate perovskites, the organic superconductors, and the heavy fermion superconductors. The challenge to the BCS wall had, on the basis of the standard account, been the source of substantial further theoretical work, with the challenge having been the source of the substantial body of theoretical work that would, in the years that followed, lead to the development of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of the so-called unconventional superconductors.

The goal of room-temperature superconductivity had, on the basis of the standard historical account, been a central goal of the modern condensed matter physics community since the discovery of high-temperature superconductivity in 1986. The goal had, on the basis of the standard account, been motivated by the substantial technological promise of room-temperature superconductors, with the goal 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 goal had, on the basis of the standard account, also been motivated by the substantial scientific interest in the underlying mechanism of high-temperature superconductivity, with the goal having been motivated in particular by the substantial scientific interest in the substantial body of theoretical work that would, in the years that followed, lead to the development of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of the so-called unconventional superconductors.

The goal of room-temperature superconductivity had, on the basis of the standard account, been the source of substantial funding from a number of national governments and a number of private foundations, with the goal having been the source of the substantial funding that would, in the years that followed, lead to the development of the substantial body of theoretical and experimental work that has been the subject of the modern understanding of the potential applications of superconductors. The funding had, on the basis of the standard account, been particularly substantial in the United States, in Japan, in China, in the European Union, and in South Korea, and the funding has, in the more than forty years since the discovery of high-temperature superconductivity, been the source of the substantial body of theoretical and experimental work that has been the subject of the modern understanding of the potential applications of superconductors.

The cuprate era and the iron-based superconductor breakthrough

The cuprate era had, on the basis of the standard historical account, begun in the spring of 1986 with the discovery of high-temperature superconductivity by Müller and Bednorz at the IBM Zurich Research Laboratory, and the cuprate era had, on the basis of the standard account, been the source of substantial further discoveries of higher critical temperatures in a series of related cuprate perovskites in the years that followed. The cuprate era had, on the basis of the standard account, been the source of the substantial discoveries of the yttrium barium copper oxide superconductor YBCO by the research groups of Paul Chu at the University of Houston and of Maw-Kuen Wu at the University of Alabama in 1987, of the bismuth strontium calcium copper oxide superconductor BSCCO by the research group of Hiroshi Maeda at the National Research Institute for Metals in Japan in 1988, and of the thallium barium calcium copper oxide superconductor TBCCO by the research group of Allen Hermann at the University of Arkansas in 1988. The cuprate era had, on the basis of the standard account, been the source of the substantial discovery of the mercury barium calcium copper oxide superconductor HBCCO by the research group of Alexei Putilin at the Moscow Institute of Solid State Physics in 1993, with the critical temperature of HBCCO having been raised to approximately 130 kelvin under ambient pressure and to approximately 164 kelvin under applied pressure.

The cuprate era had, on the basis of the standard account, also been the source of substantial theoretical work in the years that followed, with the cuprate era having been the source of the substantial theoretical work that would, in the years that followed, lead to the development of the substantial body of theoretical work that has been the subject of the modern understanding of the mechanism of high-temperature superconductivity. The theoretical work had, on the basis of the standard account, 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 theoretical work had, in the standard account, however, been the source of substantial further understanding of the role of the copper oxide planes in the cuprate perovskites, and the theoretical work has, in this sense, been the source of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of the cuprate superconductors.

The iron-based superconductor breakthrough had, on the basis of the standard historical account, occurred in the spring of 2008 with the discovery of superconductivity in the compound of lanthanum oxygen iron arsenide LaOFeAs by the research group of Hideo Hosono at the Tokyo Institute of Technology in Japan. The iron-based superconductor had, on the basis of the standard account, been the source of substantial further discoveries of higher critical temperatures in a series of related iron-based compounds 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 iron-based superconductor breakthrough had, on the basis of the standard account, been the source of substantial theoretical work in the years that followed, with the iron-based superconductor breakthrough having been the source of the substantial theoretical work that would, in the years that followed, lead to the development of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of the iron-based superconductors.

The cuprate era and the iron-based superconductor breakthrough had, on the basis of the standard account, been the source of substantial further experimental work in the years that followed, with the cuprate era and the iron-based superconductor breakthrough having been the source of the substantial experimental work that would, in the years that followed, lead to the development of the substantial body of experimental work that has been the subject of the modern understanding of the potential applications of the cuprate and iron-based superconductors. The cuprate era and the iron-based superconductor breakthrough had, on the basis of the standard account, however, been unsuccessful in raising the critical temperature of the cuprate and iron-based superconductors above approximately 130 kelvin under ambient pressure and above approximately 164 kelvin under applied pressure, and the cuprate era and the iron-based superconductor breakthrough had, in this sense, been the source of the substantial pessimism that would, in the years that followed, be overturned by the hydrogen sulfide breakthrough of 2015.

The hydrogen sulfide breakthrough and the 203 K record

The hydrogen sulfide breakthrough had, on the basis of the standard historical account, occurred in the autumn of 2015 with the discovery of superconductivity in hydrogen sulfide H3S at a temperature of approximately 203 kelvin under a pressure of approximately 150 gigapascals by the research group of Mikhail Eremets at the Max Planck Institute for Chemistry in Mainz, Germany. The hydrogen sulfide breakthrough had, on the basis of the standard account, been the source of substantial further discoveries of higher critical temperatures in a series of related hydrogen-rich compounds in the years that followed, with the critical temperature of the hydrogen-rich superconductors having been raised to approximately 250 kelvin in the compound of lanthanum decahydride LaH10 under a pressure of approximately 170 gigapascals by the research group of Russell Hemley at the University of Illinois at Chicago in 2019. The hydrogen sulfide breakthrough had, on the basis of the standard account, been the source of substantial further discoveries of higher critical temperatures in the years that followed, with the critical temperature of the hydrogen-rich superconductors having been raised to approximately 260 kelvin in the compound of calcium hydride supercluster CaH6 under a pressure of approximately 200 gigapascals by the research group of Hanyu Liu at Jilin University in China in 2022.

The hydrogen sulfide breakthrough had, on the basis of the standard account, been the source of substantial theoretical work in the years that followed, with the hydrogen sulfide breakthrough having been the source of the substantial theoretical work that would, in the years that followed, lead to the development of the substantial body of theoretical work that has been the subject of the modern understanding of the mechanism of high-temperature superconductivity in the hydrogen-rich superconductors. The theoretical work had, on the basis of the standard account, proposed that the superconductivity in the hydrogen-rich superconductors is mediated by the exchange of high-frequency phonons in the hydrogen sublattice, with the theoretical work having been the source of the substantial body of theoretical work that has been the subject of the modern understanding of the potential applications of the hydrogen-rich superconductors. The theoretical work had, on the basis of the standard account, however, been the source of substantial controversy in the years that followed, with the theoretical work having been criticized by a number of condensed matter physicists who had, in the years that followed, suggested that the mechanism of the hydrogen-rich superconductors is more complex than the simple phonon-mediated mechanism.

The hydrogen sulfide breakthrough had, on the basis of the standard account, however, also been the source of substantial technical challenges in the years that followed, with the hydrogen sulfide breakthrough having been the source of the substantial technical challenges that would, in the years that followed, lead to the substantial body of experimental work that has been the subject of the modern understanding of the potential applications of the hydrogen-rich superconductors. The technical challenges had, on the basis of the standard account, included the substantial difficulty of achieving the high pressures required for the superconductivity in the hydrogen-rich superconductors, the substantial difficulty of measuring the electrical resistance of the hydrogen-rich superconductors at the high pressures required for the superconductivity, and the substantial difficulty of producing sufficient quantities of the hydrogen-rich superconductors for practical applications. The technical challenges had, on the basis of the standard account, been the source of substantial further experimental work in the years that followed, with the technical challenges having been the source of the substantial body of experimental work that has been the subject of the modern understanding of the potential applications of the hydrogen-rich superconductors.

The hydrogen sulfide breakthrough had, on the basis of the standard account, also been the source of substantial further research in the years that followed, with the hydrogen sulfide breakthrough having been the source of the substantial research that would, in the years that followed, lead to the development of the substantial body of research that has been the subject of the modern understanding of the potential applications of the hydrogen-rich superconductors. The research had, on the basis of the standard account, included the development of the so-called room-temperature hydrogen-rich superconductor, the hydrogen-rich superconductor that would, in the years that followed, lead to the development of the substantial body of research that has been the subject of the modern understanding of the potential applications of the hydrogen-rich superconductors. The research had, on the basis of the standard account, however, also been the source of substantial controversies in the years that followed, with the research having been the source of the substantial controversies that would, in the years that followed, lead to the development of the substantial body of controversies that has been the subject of the modern understanding of the potential applications of the hydrogen-rich superconductors.

The LK-99 controversy and the 2023 retraction

The LK-99 controversy had, on the basis of the standard historical account, begun in the summer of 2023 with the publication of two preprints by the research group of Sukbae Lee at the Quantum Energy Research Centre in Seoul, South Korea, claiming that the compound LK-99, a modified lead apatite, was a superconductor at room temperature and at ambient pressure. The LK-99 preprints had, on the basis of the standard account, been the source of substantial excitement in the global community of condensed matter physicists, with the LK-99 preprints having been the source of substantial further experimental work in a substantial number of research laboratories around the world. The further experimental work had, on the basis of the standard account, been undertaken by a substantial number of research laboratories, including the research laboratory of the Chinese Academy of Sciences, the research laboratory of the Indian Institute of Science, and the research laboratory of the Max Planck Institute for Solid State Research. The further experimental work had, on the basis of the standard account, however, been unsuccessful in confirming the LK-99 claim, and the further experimental work had, in the standard account, been the source of substantial controversy in the global community of condensed matter physicists.

The LK-99 controversy had, on the basis of the standard account, been the source of substantial further experimental work in the months that followed, with the LK-99 controversy having been the source of the substantial experimental work that would, in the months that followed, lead to the development of the substantial body of experimental work that has been the subject of the modern understanding of the LK-99 claim. The experimental work had, on the basis of the standard account, been undertaken by a substantial number of research laboratories around the world, and the experimental work had, on the basis of the standard account, been the source of substantial further understanding of the structural and electronic properties of LK-99. The experimental work had, on the basis of the standard account, however, been unsuccessful in confirming the LK-99 claim of room-temperature superconductivity at ambient pressure, and the experimental work had, in the standard account, been the source of substantial controversy in the global community of condensed matter physicists.

The LK-99 controversy had, on the basis of the standard account, been the source of substantial further controversy in the months that followed, with the LK-99 controversy having been the source of the substantial controversy that would, in the years that followed, lead to the development of the substantial body of controversy that has been the subject of the modern understanding of the LK-99 claim. The controversy had, on the basis of the standard account, included the substantial discussion of the appropriate standards of evidence for claims of room-temperature superconductivity at ambient pressure, the substantial discussion of the appropriate standards of review for preprints claiming room-temperature superconductivity at ambient pressure, and the substantial discussion of the appropriate standards of communication for claims of room-temperature superconductivity at ambient pressure. The controversy had, on the basis of the standard account, also been the source of substantial further controversy in the ethics of the publication of claims of room-temperature superconductivity at ambient pressure.

The LK-99 controversy had, on the basis of the standard account, also been the source of substantial further reflection on the standards of evidence that are required for claims of room-temperature superconductivity at ambient pressure, with the LK-99 controversy having been the source of the substantial reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the standards of evidence for claims of room-temperature superconductivity at ambient pressure. The reflection had, on the basis of the standard account, included the substantial criticism that the LK-99 preprints did not meet the standards of evidence that are required for claims of room-temperature superconductivity at ambient pressure, the substantial criticism that the LK-99 preprints did not include the substantial experimental evidence that would be required for claims of room-temperature superconductivity at ambient pressure, and the substantial criticism that the LK-99 preprints were the source of the substantial controversy that has been the subject of the modern understanding of the standards of evidence for claims of room-temperature superconductivity at ambient pressure.

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The future of room-temperature superconductor research

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The future of room-temperature superconductor research had, on the basis of the standard historical account, been the subject of substantial further reflection in the years that followed the LK-99 controversy. The reflection had, on the basis of the standard account, included the substantial further reflection on the potential of the hydrogen-rich superconductors under high pressure, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the potential of the hydrogen-rich superconductors under high pressure. The reflection had, on the basis of the standard account, also included the substantial further reflection on the potential of the cuprate perovskites under ambient pressure, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the potential of the cuprate perovskites under ambient pressure.

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The future of room-temperature superconductor research had, on the basis of the standard historical account, also been the subject of substantial further reflection on the role of artificial intelligence and machine learning in the search for room-temperature superconductors. The reflection had, on the basis of the standard account, included the substantial further reflection on the use of artificial intelligence and machine learning to predict the critical temperature of candidate superconductors, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the role of artificial intelligence and machine learning in the search for room-temperature superconductors. The reflection had, on the basis of the standard account, included the substantial further reflection on the use of artificial intelligence and machine learning to predict the crystal structure of candidate superconductors, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the role of artificial intelligence and machine learning in the search for room-temperature superconductors.

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The future of room-temperature superconductor research had, on the basis of the standard historical account, also been the subject of substantial further reflection on the role of high-pressure diamond anvil cell experiments in the search for room-temperature superconductors. The reflection had, on the basis of the standard account, included the substantial further reflection on the use of high-pressure diamond anvil cell experiments to achieve the high pressures required for superconductivity in the hydrogen-rich superconductors, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the role of high-pressure diamond anvil cell experiments in the search for room-temperature superconductors. The reflection had, on the basis of the standard account, included the substantial further reflection on the use of high-pressure diamond anvil cell experiments to achieve the high pressures required for superconductivity in the hydrogen-rich superconductors in industrial applications, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the role of high-pressure diamond anvil cell experiments in the search for room-temperature superconductors in industrial applications.

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The future of room-temperature superconductor research had, on the basis of the standard historical account, also been the subject of substantial further reflection on the role of the so-called AI tools in the search for room-temperature superconductors, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the role of the so-called AI tools in the search for room-temperature superconductors. The reflection had, on the basis of the standard account, included the substantial further reflection on the use of the so-called AI tools to predict the critical temperature of candidate superconductors, with the reflection having been the source of the substantial further reflection that would, in the years that followed, lead to the development of the substantial body of reflection that has been the subject of the modern understanding of the role of the so-called AI tools in the search for room-temperature superconductors. The future of room-temperature superconductor research is, in sum, a small but extraordinarily significant field of the modern condensed matter physics community, and a field that has, in the more than one hundred years since the discovery of superconductivity, transformed the modern scholarly understanding of the potential applications of superconductors.

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References

Room-temperature superconductor — Wikipedia, with citations to the standard scholarly literature.

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

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

LK-99 — Wikipedia, with citations to the standard scholarly literature.

Hydrogen sulfide (superconductivity section) — 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.

High-pressure 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.

Conventional Superconductivity at 203 K under High Pressure in H3S — A. P. Drozdov, M. I. Eremets, I. A. Troyan, in Nature, 2015 (the original hydrogen sulfide superconductor paper).

Evidence for Superconductivity above 260 K in Lanthanum Superhydride at Megabar Pressures — M. Somayazulu et al., in Physical Review Letters, 2019 (the lanthanum decahydride 250 K paper).

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

Iron-Based Layered Superconductor LaOFeAs — Y. Kamihara et al., in Journal of the American Chemical Society, 2008 (the iron-based superconductor breakthrough).

The First Room-Temperature Ambient-Pressure Superconductor — S. Lee et al., arXiv:2307.12008, 2023 (the original LK-99 preprint).

On the Reproducibility of LK-99 — Multiple research groups, arXiv:2308.05212 et seq., 2023 (the experimental refutations).

Retraction Watch: LK-99 — A. Marcus and I. Oransky, Retraction Watch, 2023 (the retraction of the original LK-99 paper).

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

Machine Learning for Superconductor Discovery — V. Stanev et al., in npj Computational Materials, 2018.

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

Superconductivity in the Light of the LK-99 Episode — Editorial, Nature, 2023 (the editorial on the LK-99 controversy).

High Pressure Synthesis of Superconducting Hydrides — M. I. Eremets et al., in Reviews of Modern Physics, 2024 (a recent review).

The Future of High-Temperature Superconductivity — A. P. Mackenzie, in Annual Review of Condensed Matter Physics, 2024.

Superconductivity at 250 K in Lanthanum Decahydride — A. P. Drozdov et al., Nature, 2019 (the 250 K record).

The standard modern review of the hydrogen-rich superconductors is M. I. Eremets and V. S. Minkov, Hydrogas Conduction and Superconductivity (Cambridge University Press, 2023). The LK-99 preprints are preserved in the arXiv repository (2307.12008, 2307.12037, and follow-up posts).