High-Temperature Superconducting Phases in Cerium Superhydride with a Tc up to 115 K below a Pressure of 1 Megabar

2021/01/06 by Wuhao Chen, Dmitrii V. Semenok, Dmitrii V. Semenok +7 · 4 citations
Earth and Planetary Sciences · Materials Science · Physics and Astronomy · #Cerium #Deuterium #Drop (telecommunication) #High-pressure geophysics and materials #Hydride #Hydrogen #Hydrogen Storage and Materials #Phase (matter) #Rare-earth and actinide compounds #Room-temperature superconductor #Superconductivity #cond-mat.mtrl-sci #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevlett.127.117001

published as Phys. Rev. Lett. 127, 117001 (2021)

arxiv created 2021/01/06 · openalex created_date 2021/01/18 · openalex publication_date 2021/09/09 · arxiv updated 2021/09/15 · openalex updated_date 2026/08/05

Abstract

The discoveries of high-temperature superconductivity in H₃S and LaH₁₀ have excited the search for superconductivity in compressed hydrides, finally leading to the first discovery of a room-temperature superconductor in a carbonaceous sulfur hydride. In contrast to rapidly expanding theoretical studies, high-pressure experiments on hydride superconductors are expensive and technically challenging. Here, we experimentally discovered superconductivity in two new phases, Fm3m\text\ensuremath-CeH₁₀ (SC-I phase) and P6₃/mmc\text\ensuremath-CeH₉ (SC-II phase) at pressures that are much lower (<100 GPa) than those needed to stabilize other polyhydride superconductors. Superconductivity was evidenced by a sharp drop of the electrical resistance to zero and decreased critical temperature in deuterated samples and in external magnetic field. SC-I has T_c=115 K at 95 GPa, showing an expected decrease in further compression due to the decrease of the electron-phonon coupling (EPC) coefficient \ensuremathλ (from 2.0 at 100 GPa to 0.8 at 200 GPa). SC-II has T_c=57 K at 88 GPa, rapidly increasing to a maximum T_c\ensuremath∼100 K at 130 GPa, and then decreasing in further compression. According to the theoretical calculation, this is due to a maximum of \ensuremathλ at the phase transition from P6₃/mmc\text\ensuremath-CeH₉ into a symmetry-broken modification C2/c\text\ensuremath-CeH₉. The pressure-temperature conditions of synthesis affect the actual hydrogen content and the actual value of T_c. Anomalously low pressures of stability of cerium superhydrides make them appealing for studies of superhydrides and for designing new superhydrides with stability at even lower pressures.

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