roomtsc
A project to find a material that superconducts at room temperature and one atmosphere.
No such material is known. This site keeps the experimental record, lists new results as they are published, and carries the project's paper, which sets out the physical limits and specifies the model and the tests it has to pass.
Where the record stands
The target is 300 K at one atmosphere. The highest reproduced transition temperature at one atmosphere is less than half of that, and the highest reproduced at any pressure needs 170 GPa, about 1.7 million atmospheres.
| Highest | Tc | Material | Pressure | Standing |
|---|---|---|---|---|
| Stable phase at one atmosphere | 133 to 138 K | HgBa2Ca2Cu3O8+δ | 1 atm | Reproduced widely since 1993. Schilling et al., Nature 363, 56 (1993) |
| Kept at one atmosphere after a pressure quench | 151 K onset | HgBa2Ca2Cu3O8+δ | 1 atm, metastable below about 170 K | One group, 2026. Deng et al., PNAS 123, e2536178123 (2026) |
| Reproduced at any pressure | 250 K | LaH10 | 170 GPa | Reproduced in Beijing (2020) and Jilin (2025). Drozdov et al., Nature 569, 528 (2019) |
| Claimed at any pressure | 298 K onset | LaSc2H24 | 260 GPa | Preprint. No magnetic or isotope data. Seven failed attempts by a second group. Song et al., arXiv:2510.01273 (2025) |
News
Published results that bear on the target, with what each one does and does not show.
- A calculation in Physical Review B describes LaSc2H24 as an isotropic single-gap superconductor and LaH10 as an anisotropic two-gap one. The paper contains no measurement. The three journal papers we could find on the compound are all theory. Wang et al., Phys. Rev. B 114, 154501
- TeH4 superconducts at 91 K at 263 GPa, a pressure inside the range of the LaSc2H24 claim. Zhu et al., arXiv:2608.30139
- Seven attempts to make LaSc2H24 at 250 to 280 GPa from melted La-Sc alloy found no superconductivity between 245 and 300 K. Three cells lost their anvils before any transport measurement, and no cell was shown by X-ray diffraction to contain the claimed phase. The result is a failed synthesis and leaves the properties of the phase untested. Semenok et al., arXiv:2605.29985v2
- Bilayer nickelate films that superconduct near 40 K at ambient pressure reach 67 to 73 K at 16 GPa. Osada et al., Nat. Mater.
- LaH10 films with a Tc of 247 K at 176 GPa stayed stable for about 300 days. Cross et al., arXiv:2608.18865
- YH6 measured at 218 to 221 K and YH9 at 235 to 237 K between 140 and 213 GPa. The accompanying anharmonic calculation caps YH10 at about 260 to 270 K. Semenok et al., arXiv:2608.11428
- A structure search of La-Sc-H at 250 GPa assigns the unidentified second phase seen in some LaSc2H24 samples to cubic La2ScH36. The paper is a calculation and reports no new measurement. Wang et al., J. Am. Chem. Soc. 148, 29932
- HgBa2Ca2Cu3O8+δ quenched from 10 to 30 GPa at 4.2 K keeps a superconducting onset of up to 151 K at ambient pressure, against 133 to 138 K for the stable phase. The quenched state is metastable and has to stay below about 170 K. It has not been independently reproduced. Deng et al., PNAS 123, e2536178123
- In a cell at 165 GPa holding mainly LaH12, radio-frequency transmission drops below about 267 to 279 K and the proton NMR signal is suppressed below 260 K in a 7 T field. No four-probe resistance was measured on these cells and the samples contain more than one phase. Semenok et al., Adv. Sci. 13, e20701
- Resistive onsets of 271 to 298 K reported in LaSc2H24 between 195 and 266 GPa, with zero resistance claimed in two cells. The authors give the 10 to 20 micrometre sample size as the reason for having no magnetic data. No journal version had appeared by 6 October 2026. Song et al., arXiv:2510.01273
Project updates
- Draft 4 of the paper is online: Room temperature, one atmosphere.
Paper
Room temperature, one atmosphere
What limits superconductivity at room temperature and ambient pressure, how far published calculations and experiments stand from each limit, and what a model built to find such a material should estimate and be tested on.