NV quantum sensing of materials under pressure: a new lens on the superconducting hydride controversy

The discovery of superconducting transition temperatures (Tc) above 250 K in pressurized hydrides has sparked new hope for realizing ambient-condition superconductivity. Although electrical resistance measurements have provided significant evidence for superconductivity in various hydrides, magnetic evidence remains limited due to the extreme conditions required for these studies. Traditional methods are often compromised by background noise, which keeps the superconductivity in these hydrides controversial. Using a diamond anvil cell implanted with nitrogen-vacancy (NV) color centers, we characterize LaHx, a superconductor with the highest reported Tc, at pressures exceeding 1.6 Mbar. Alongside electrical transport measurements, we image Meissner suppression and flux trapping, providing spatially resolved insights that reveal how the local superconducting properties evolve with pressure and temperature. Our work demonstrates the feasibility of NV-widefield imaging under extreme conditions, offering a fresh perspective on the debate surrounding superconducting properties in hydrides under extreme high-pressure conditions. This opens new possibilities for resolving long-standing questions in hydride superconductivity and guiding future synthesis efforts.