Sustainable high critical temperature in a hydrocarbon superconductor

TL;DR

This study discovers a hydrocarbon superconductor, LaPhenanthrene, with a high and stable critical temperature of 12.3 K under high pressure, revealing pressure's role in tuning electron correlations and superconductivity.

Contribution

It demonstrates that applying high pressure stabilizes and enhances superconductivity in LaPhenanthrene, a hydrocarbon superconductor, over a wide pressure range, which was previously limited.

Findings

$T_{C}$ increases from 4.8 K to 12.3 K at 18.4 GPa

High $T_{C}$ remains stable over 61 GPa of pressure

Superconductivity correlates with the angle $eta$ of the unit cell

Abstract

Organic superconductors are unique materials with a crystal structure made primarily of a complex carbon based network, an element associated directly with life, which were postulated to have a high critical temperature, $T_{C}$, even above room temperature, from a theoretical viewpoint. Pressure plays an essential role in the study of superconductivity in such organic materials, including creation of the first organic superconductor as well as the achievement of the highest $T_{C}$ of 14.2 K for charge transfer salts and 38 K for metal-doped fullerides. However, superconductivity in these organic systems is only sustainable within a very narrow pressure range (a few GPa) and is readily destroyed upon further compression. Here we report high-pressure magnetic susceptibility and structure measurements on a newly discovered superconductor, LaPhenanthrene. It is found that the application of pressure not only significantly increases $T_{C}$ from its ambient-pressure value of 4.8 K to 12.3 K at 18.4 GPa but also stabilizes the high $T_{C}$ over the entire pressure range (61 GPa) of the study. The evolution of $T_{C}$ with pressure is closely correlated with the angle $\beta$ of the monoclinic unit cell. Both $T_{C}$ and $\beta$ change sharply with increasing pressure initially but remain constant above 40 GPa, indicating that molecule orientation is essential to superconductivity. These behaviors can be understood in terms of pressure tuning of electron correlations, illustrating the unconventional nature of superconductivity in these hydrocarbon superconductors.