Superconductivity is the phenomenon where a material conducts electric current with zero resistance. First discovered in 1911 by Heike Kamerlingh Onnes (who cooled mercury to 4 K), it means a current can, in principle, circulate forever without energy loss. In normal metals, electrons scatter off vibrating atoms, wasting about 5–10% of generated electrical power as heat in transmission. Superconductors eliminate that loss entirely. They have found niche uses (e.g. MRI magnets, particle colliders, maglev trains) but only under severe cooling. In a superconductor, electrons pair up (forming “Cooper pairs”) and move in lock-step, so that scattering stops. Materials with higher critical temperatures (Tc) require less cooling, sparking the long-standing search for superconductivity at ever-warmer conditions.
The Quest for Higher Temperatures
For decades superconductivity was only seen near absolute zero. In 1986–1987 a breakthrough came: Georg Bednorz and Karl Müller discovered ceramic “cuprate” superconductors with much higher Tc, earning the 1987 Nobel Prize. Paul Chu and others quickly demonstrated a famous compound (YBa₂Cu₃O₇) superconducting above 90 K – high enough to use liquid nitrogen cooling. This raised hopes that someday “room-temperature” (≈290 K) superconductivity might be achieved. But despite decades of effort, all confirmed superconductors at ambient pressure still have Tc well below room temperature. The record at ordinary pressure remains around 133 K (–140 °C) for special cuprates under particular conditions. By contrast, theoretical and experimental advances in the last decade have pushed the record Tc under extreme pressure ever higher, though those materials need devices like diamond anvils to reach megabar stresses.
A schematic of lanthanum hydride (LaH₁₀), a hydrogen-rich “superhydride” that superconducts near –23 °C at ~170 gigapascals (GPa). Hydrogen atoms (purple) form a cage around a larger atom (blue), a motif that helps achieve very high Tc under pressure.
Hydrogen-Rich (“Superhydride”) Breakthroughs
A key advance has been in hydrogen-based compounds under pressure. Philip Ashcroft long predicted that metallic hydrogen (or hydrides rich in hydrogen) could superconduct at very high Tc if compressed. This came to pass in 2015: a team led by Mikhail Eremets reported that hydrogen sulfide (H₂S, which likely forms H₃S under pressure) became superconducting at an astonishing 203 K (–70 °C) when squeezed to ~150 GPa. That shattered the previous Tc record. The race continued: in 2019 Eremets’ group (in collaboration with others at the US National MagLab) found that lanthanum hydride (LaH₁₀) superconducts at around 250 K (–23 °C) under ~170 GPa. This result was recognised as a milestone and highlighted how close it brought the goal of room-temperature superconductivity under extreme conditions. (Earlier record was –70 °C.) Importantly, these achievements came only at pressures comparable to those at the Earth’s core, using diamond-anvil cells.
In 2020, researchers even reported superconductivity at 288 K (15 °C) in a more complex carbon–sulfur hydride (pressurised to ~267 GPa). Had this been confirmed, it would have been the first ambient-temperature superconductor. However, doubts surfaced soon after publication. Critics noted non‑standard data processing, and independent labs could not reproduce the effect above about 200 K. In 2022 Nature officially retracted that study, with co-authors acknowledging problems that “undermine the integrity” of the reported result. These episodes show that while hydrides have indeed achieved unprecedented Tc’s, each claim must be rigorously verified.
Failed Claims and Retractions
Alongside real breakthroughs, several high-profile claims have collapsed under scrutiny. For example, in March 2023 a team reported that a novel lutetium–hydrogen compound (with a bit of nitrogen) superconducted up to ~294 K (21 °C) at only ~1 GPa pressure. This sounded too good to be true, and many labs quickly tried to replicate it. Almost all found no zero-resistance transition – only ordinary metallic or insulating behaviour. An internal journal investigation later cited evidence of “apparent data fabrication,” and in late 2023 Nature retracted the paper at the request of eight co-authors. (This followed two earlier retractions for the same group’s papers.) Similarly, a 2020 report of 15 °C superconductivity in a hydrogen–carbon–sulfur material was withdrawn amid concerns over data handling. These failures reveals the proverbial and vital lesson: extraordinary claims require extraordinary proof. If raw resistance and magnetisation data are not shared or don’t clearly show a Meissner effect, skepticism is warranted.
The LK-99 Episode
In July 2023 another sensational claim emerged, this time for a completely different material. Two Korean scientists (Lee and Kim) posted preprints on arXiv about a modified lead-apatite crystal dubbed “LK-99” (Pb₉Cu(PO₄)₆O). They reported that this purple-colored compound levitated small magnets (suggesting the Meissner effect) and showed zero resistance below ~127 °C (400 K) at ambient pressure. Media outlets leapt on it: one headline hailed it as a “possible real solution to the energy crisis” that “could change everything”. However, experts noted the authors had no track record in superconductivity and that the sample looked nothing like known high‑Tc materials.
Within weeks, dozens of groups worldwide had synthesised LK-99. The overwhelming finding was that it is not a superconductor. Most samples exhibited ordinary resistivity (even increasing as temperature fell), and the apparent magnet levitation could be explained by tiny ferromagnetic copper-sulfide impurities, not bulk superconductivity. By mid-August 2023 a broad consensus emerged in the community: LK-99 behaves like an insulator or poor metal, with no true zero-resistance state. In other words, the initial reports were almost certainly mistaken. This episode became a cautionary tale about hype: only thorough peer review and independent replication can confirm such groundbreaking claims.
Media Hype vs. Scientific Scrutiny
The LK-99 saga exemplifies how media hype can wildly oversell unverified results. Sensational phrases (“energy crisis solved”) graced tech blogs and news sites, fueling public excitement. But seasoned scientists emphasise caution. As one industry expert bluntly put it, the field has suffered from “overly enthusiastic or deceptive” efforts and “sloppy science”. Reproducibility and raw evidence are everything in condensed-matter physics. Measurements must show clear zero resistance and the characteristic magnetic response (the Meissner effect) without tricks like subtracting backgrounds. In practice, that means even provocative new claims must survive repeated tests. When LK-99 failed those tests, the community drew back, illustrating the self-correcting nature of science.
Where the Field Stands Today
No material has yet passed peer review as an ambient-pressure, room-temperature superconductor. The current all‑time record remains the hydride family under extreme pressure (~250 K at ~170 GPa in LaH₁₀. Researchers continue to explore hydrogen-rich compounds (and related predictions) while also investigating unconventional approaches. For instance, in January 2024 a team reported one-dimensional superconductivity at 300 K (27 °C) in deliberately “wrinkled” graphite tapes – a sensational claim that, like LK-99, needs independent confirmation. Many remain skeptical pending replication.
In summary, progress has been real but hard-won. Exciting new materials keep appearing, but so do dead ends and retractions. The consensus view is cautious optimism: room-temperature superconductivity might be achievable, but it has proven elusive. As one expert quipped, “it will happen, although it is hard to tell when,” and if it does, the applications would be “all sorts of incredible”. In the meantime, scientists emphasize rigor and replication. The controversies of 2023 – Dias’s hydrides and the LK-99 fiasco – have reminded the community to double-check every result. “Serious people continue to do amazing work,” stresses physicist Peter Armitage, but only time will tell which next twist in this century‑long quest for lossless electricity will truly pan out.
Sources
Room-Temperature Superconductivity Heats Up – Communications of the ACM
https://cacm.acm.org/news/room-temperature-superconductivity-heats-up/
There’s no room-temperature superconductor yet, but the quest continues | Physics | The Guardian
https://www.theguardian.com/science/2023/sep/02/room-temperature-superconductor-south-korea-lk-99-nuclear-fusion-maglev
“Superhydride” Shows Superconductivity at Record-Warm Temperature – MagLab
https://nationalmaglab.org/news-events/news/superhydride-superconductivity/
First-principles study of superconducting hydrogen sulfide at pressure up to 500 GPa | Scientific Reports
https://www.nature.com/articles/s41598-017-04714-5?error=cookies_not_supported&code=172ed9ce-d04c-423d-8f17-c2e5ca56fcf9
Room-Temperature Superconductivity Claim Falls Apart [Update] | Quanta Magazine
https://www.quantamagazine.org/room-temperature-superconductivity-claim-falls-apart-update-20201014/
Nature Retracts Controversial Room-Temperature Superconductor Study | Scientific American
https://www.scientificamerican.com/article/nature-retracts-controversial-room-temperature-superconductor-study/
[2307.12037] Superconductor Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O showing levitation at room temperature and atmospheric pressure and mechanism https://arxiv.org/abs/2307.12037
