Possible Pairing Mechanisms of PuCoGa${}_5$ Superconductor

Abstract

We examine possible pairing mechanisms of superconductivity in PuCoGa${}_5$ based on spin-fluctuations or phonons as mediating bosons. We consider experimental data of specific heat C(T) and resistivity $\rho (T)$ as input to determine a consistent scattering boson with the superconducting transition temperature of 18.5K in PuCoGa${}_5$. Irrespective to the type of boson, the characteristic boson frequency is found to be $\sim 150K$ from the resistivity fitting. The spin fluctuation model is most consistent with the experimental resistivity, successfully explaining the anomalous temperature dependence ($\sim \frac{T^2}{150K+T}$) at low temperatures as well as the saturation behavior at high temperatures. Assuming that the pairing state is non s-wave, the large residual resistivity ${\rho }_{imp}\sim 20\mu \Omega cm\sim 120K$ suggests that an ideally pure sample of PuCoGa${}_5$ would have a maximum T${}_c$ of 39 K.

6 pages, 5 figures