Insulator-conductor transition of hydrogen on the melt curve

The metallization of hydrogen has fundamental applications in the material and planetary sciences. One area of interest is the isotope difference in metallization, with liquid hydrogen being predicted to become conducting at lower pressures compared to otherwise equal deuterium. Another, less frequently considered variable is the hydrogen nuclear spin state, which changes the initial entropy significantly and is expected to influence the entropy during compression.



In a series of compression experiments on OMEGA, solid para-hydrogen and normal hydrogen was ramp-compressed near-isentropically. Velocity interferometry and optical pyrometry were used to reconstruct the pressure and temperature history of the target. Our analysis suggests that these experiments reached several hundred gigapascals, producing conducting hydrogen on the melt curve. Comparisons will be presented between (1) the responses of para-hydrogen and normal hydrogen to identical drives and (2) the metallization conditions of our hydrogen samples compared to deuterium, as presented in literature.



This material was funded by the Center for Matter at Atomic Pressures (CMAP), a National Science Foundation (NSF) Physics Frontiers Center, under Award PHY-2020249.