Diamond Anvil Cells as Gateways to Extreme Phases: H₃S, LaH₁₀ and Metallic Hydrogen

In this talk, I will introduce high-pressure physics as a method for tuning the lattice and electronic properties of condensed matter. Using diamond anvil cells, we can achieve static pressures of 300-400 GPa and beyond, compressing samples to conditions comparable to those in the deep interiors of giant planets. Under these extreme conditions, simple elements, such as hydrogen and hydrogen-rich compounds, change their bonding, become metals, and, in some cases, superconduct with critical temperatures close to room temperature.

I will briefly review the set of experimental techniques and methods we have developed: diamond anvil cells with micro-fabricated diamonds capable of conducting four-probe resistance measurements at multi-megabar pressures, and planar tunnelling junctions integrated on the diamond culet. I will show how these methods enabled the discovery and characterisation of high-Tc hydride superconductors such as H₃S and LaH₁₀. Finally, I will present our electrical and Raman measurements on dense hydrogen, where we observed metallic-like transport and loss of Raman activity, providing evidence for the long-sought transition to metallic hydrogen.

If you would like to meet with Sasha during his visit, please contact Susan LaMoreaux.