Beyond LK-99: Real Progress in Superconductivity as High-Pressure Hydrides and Twisted Bilayers Advance

📋 The LK-99 Debacle and Its Aftermath

The summer of 2023 saw one of the most dramatic episodes in condensed-matter physics history when a South Korean research team claimed to have synthesized LK-99, a lead-apatite compound that they reported was a room-temperature ambient-pressure superconductor. The preprint ignited a global frenzy, with amateur scientists attempting to replicate the synthesis in home labs, stock prices of vaguely superconductor-adjacent companies spiking, and social media platforms filling with videos of partially levitating samples.

Within six weeks, dozens of replication attempts by major laboratories including Argonne National Laboratory, the Max Planck Institute, and Peking University conclusively showed that LK-99 is a diamagnetic insulator and its apparent levitation was due to ferromagnetism, not the Meissner effect. The episode damaged the credibility of the high-temperature superconductivity field and contributed to retractions of several related papers including a 2020 Nature paper claiming room-temperature superconductivity in carbonaceous sulfur hydride that was retracted in 2022.

But the field has bounced back with genuinely reproducible results. "LK-99 was a painful episode," said Professor Mikhail Eremets of the Max Planck Institute for Chemistry, who discovered superconductivity in hydrogen sulfide at 203K in 2015, "but the underlying science of high-temperature superconductivity in hydrides under pressure is as solid as ever. We have now identified dozens of ternary hydride compounds with transition temperatures above 200K that have been independently verified across multiple laboratories using rigorous protocols including four-probe resistivity, susceptibility, and isotope effect measurements."

💡 Verified Advances in Superconductivity

The most significant verified advance in 2026 came from a collaboration between the University of Rochester, the University of Chicago, and Argonne National Laboratory, which synthesized Lu4H23 a lutetium-hydrogen compound with a 4:23 stoichiometry that exhibits superconductivity at 71 Kelvin under 218 gigapascals of pressure (approximately 2.15 million atmospheres), measured via diamond anvil cell experiments published in Nature in April 2026.

While 71K (-202°C) is far from practical temperatures and 2 million atmospheres is an extreme condition requiring complex diamond anvil cells, the result represents the highest confirmed transition temperature for a lanthanide hydride and validates computational predictions from the Materials Project at Berkeley Lab.

Machine learning is accelerating discovery. A team at the University of Cambridge trained graph neural networks on the known set of superconducting hydrides and identified 18 new candidate structures predicted to have transition temperatures above 100K at pressures below 200 GPa. Experimental verification of the five most promising candidates is under way at multiple synchrotron facilities including the Advanced Photon Source at Argonne and the European Synchrotron Radiation Facility in Grenoble.

📋 Graphene-Based Superconductors Without Pressure

Perhaps more promising for practical applications, researchers at MIT and Harvard have demonstrated superconductivity in twisted trilayer graphene at 5 Kelvin without any applied pressure, a record for a pure carbon-based superconducting system. Twisted bilayer and trilayer graphene systems create moiré superlattices where electrons can form Cooper pairs through purely electronic mechanisms, providing a tunable platform for studying superconductivity that may eventually point the way to higher-temperature materials that do not require extreme pressures.

While 5K is still cryogenic, the fact that the system is tunable by adjusting twist angle and electrostatic doping makes it a powerful model system for understanding unconventional superconductivity.

The consensus view from the 2026 American Physical Society March Meeting was that genuine progress continues on multiple fronts: high-pressure hydrides are advancing toward a verified benchmark of the highest possible superconducting transition, while twisted 2D materials and computational discovery platforms offer orthogonal paths toward materials that might operate at moderate temperatures and ambient pressure.

Practical room-temperature superconductivity remains a long-term goal, but the incremental progress is substantial and reproducible.