Superconducting High Pressure Phases Composed of Hydrogen and Iodine

TL;DR

This study predicts new high-pressure iodine polyhydride phases with potential superconductivity, highlighting how hydrogen incorporation enhances their electronic properties and critical temperatures.

Contribution

The paper introduces three novel iodine polyhydride phases stable under high pressure, expanding the understanding of hydrogen-rich compounds and their superconducting potential.

Findings

Insulating P1-H5I stable between 30-90 GPa.

Metallic H2I and H4I phases stable at higher pressures.

Estimated Tc of 7.8 K for H2I and 17.5 K for H4I at 100 GPa.

Abstract

Evolutionary structure searches predict three new phases of iodine polyhydrides stable under pressure. Insulating P1-H5I, consisting of zigzag chains of HI (delta+)and H2(delta-) molecules, is stable between 30-90 GPa. Cmcm-H2I and P6/mmm-H4I are found on the 100, 150 and 200 GPa convex hulls. These two phases are good metals, even at 1 atm, because they consist of monoatomic lattices of iodine. At 100 GPa the Tc of H2I and H4I are estimated to be 7.8 and 17.5 K, respectively. The increase in Tc relative to elemental iodine results from a larger omega-log from the light mass of hydrogen, and an enhanced lambda from modes containing H/I and H/H vibrations.