Evidence Against Superconductivity in Flux Trapping Experiments on Hydrides Under High Pressure

It has recently been reported that hydrogen-rich materials under high-pressure trap magnetic flux [1], a tell-tale signature of superconductivity. We argue that the evidence in that paper does not support superconductivity, because the trapped moment under ZFC was found to be linear in field, rather than quadratic as expected [2]. Furthermore those results are incompatible with the magnetization measurements on the same samples reported in Ref. [3], under the assumption that they originate in superconductivity. Namely, they imply that the samples can trap flux even when the flux does not penetrate the sample, and that supercurrents that trap magnetic flux are much larger than those that shield magnetic flux, which is unphysical. Instead, we propose that the magnetic signatures observed in both experiments result from localized magnetic moments in the sample and its environment rather than electric supercurrents. Together with other experimental evidence analyzed earlier [4], this indicates that these materials are not superconductors.

 

[1] V. S. Minkov et al, arXiv:2206.14108 (2022).

[2] J. E. Hirsch and F. Marsiglio, J Supercond Nov Magn 35, 3141–3145 (2022).

[3] V. S. Minkov et al, Nat Commun 13, 3194 (2022).

[4] J. E. Hirsch and F. Marsiglio, MRE 7, 058401 (2022).