Universal resistivity from electron-phonon interaction based on Einstein model: Application to near-room temperature superconductors
Udomsilp Pinsook, Pacharapol Tanthum
Abstract
We have applied Bloch-Grüneisen (BG) formula, together with Einstein model, to give the description to the temperature dependent resistivity in the metal phase of several recently reported compounds, which transform into a conventional superconductor at a high value of the critical temperature, T c . We found that the behavior of the resistivity as a function of temperature is in good agreement with the derived formula, especially when T c is quite high and the phonon modes are dominated by optical phonons. Furthermore, we discovered that several compounds in this class possess the so-called universal resistivity, which means that under a proper temperature scaling, the scaled resistivity behaves as a universal function, regardless of the types of the compounds. The free parameter in the model, θ E , shows a strong correlation with the logarithmic average frequency, ω ln . It can serve as a reasonable approximation of ω ln , which can be compared directly with that from the celebrated Allen-Dynes formula. We showed the extracted data of several novel superhydride compounds, such as H 3 S, ThH 9 , ThH 10 , YD 6 , LaH 10 , and LaCeH 20 , LaBeH 8 , CaMgH x . We also compared our results with the available data from experiments and the density functional theory (DFT).