"Observation of the transition to metal hydrogen", Paul Loubeyre - CEA, Arpajon

INVITATION

ESRF-ILL Online Colloquium

"Observation of the transition to metal hydrogen"

Friday, September 24th at 14:00

Please click here to watch the replay

Abstract

Understanding how and when molecular solid hydrogen may transform into a metal has stimulated many theoretical works since the 30’s. It is still an opened theoretical question and an experimental challenge. The quest for metal hydrogen has pushed major developments of modern experimental high pressure physics and still various claims of its observation have remained unconfirmed.

In 2020, we observed and characterized the transition to metal hydrogen near 425 GPa at 80 K [1]. Very recently, the transition to metal deuterium has also been observed, showing a significant isotopic shift in pressure. In this talk, our experimental strategy will be presented as following three steps namely: 1) Demonstrate the possibility to generate pressures well over 400 GPa ( that is the limit of the conventional Diamond Anvil Cell (DAC)) by loading hydrogen in the recently developed Toroidal-DAC[2]; 2) Exhibit a reliable non-intrusive signature of the insulator-metal phase transition, i.e. total IR absorption by using the IR synchrotron radiation at SOLEIL; 3) Record combined infrared, Raman and visible observation measurements to disclose the physics at stake at the insulator-metal transition. 

On-going experimental developments to further characterize the intriguing properties of metal hydrogen will be discussed.

[1] Synchrotron infra-red spectroscopic evidence of the probable transition to metal hydrogen. P. Loubeyre, F. Occelli and P. Dumas.  Nature 577, 631 (2020).

[2] Toroidal diamond anvil cell for fine measurements under extreme static pressures: data on Al, Ar and Au up to 603 GPa. A. Dewaele, P. Loubeyre, F. Occelli, O. Marie and M. Mezouar. Nature Com. 9, 2913 (2018).