Dynamical stability and superconductivity of (Ce,La)H9 under high pressure

TL;DR

This study uses theoretical methods to analyze the stability and superconducting properties of (Ce,La)H9 under high pressure, revealing its potential for high-temperature superconductivity around 87K at 200GPa.

Contribution

It provides the first theoretical investigation of (Ce,La)H9's stability and superconductivity, combining phonon analysis and molecular dynamics simulations.

Findings

(Ce,La)H9 becomes stable at 203K under high pressure.

The electron-phonon coupling constant λ reaches 3.0 at 200GPa.

Predicted superconducting critical temperature Tc is 87K at 200GPa.

Abstract

Recent experiments have shown that CeH9 and (Ce,La)H9 can be synthesized under high pressure between 90-170GPa and become a superconductor with a high value of superconducting critical temperature (Tc) between 100-200K. In this work, we performed a theoretical study of a (Ce,La)H9 compound where the Ce:La ratio is equal to 1. We used the density functional theory and the {\it ab initio} molecular dynamics (AIMD) method. From the phonon dispersion, there exist some unstable modes around the K-point phonons. Then, we performed AIMD simulation at around 203K and found that the compound becomes stable. The superconducting spectral function can be calculated. We found that $\lambda$ is as high as 3.0 at 200GPa. By using Allen-Dynes-modified McMillan equation in the strong coupling regime, we found that Tc = 87K at 200GPa.