Metallic deuterium made at pressures rivalling those found at the centre of a planet

The French group that in 2020 produced the most convincing evidence yet that hydrogen forms a metallic state at high pressures has now shown that at even higher pressures deuterium can become metallic. These findings support the theory behind the 2020 claims, and may also assist in the study of novel high-pressure superconductors.

In theory, all elements become metallic at sufficiently high pressures as the atoms are squeezed close enough that the electrons become delocalised. Modelling the metallisation transitions precisely, however, is extremely difficult. The metallisation of hydrogen has long attracted particular interest, partly because it is the simplest system but also because quantum delocalisation should be apparent in the nucleus as well as the electrons.