Gallium substitution in PuCoGa5

TL;DR

This study explores substituting gallium with other elements in PuCoGa5, revealing limited successful synthesis, reduced critical temperatures, and significant electronic structure changes, with no isotope effect observed on Tc.

Contribution

It reports successful synthesis of PuCoGa4Al and PuCoGa4Ge, analyzes their structural and electronic properties, and investigates isotope effects, providing new insights into the material's superconductivity.

Findings

Successful synthesis of PuCoGa4Al and PuCoGa4Ge with 20% substitution.

Reduced critical temperatures in substituted compounds.

Significant changes in Fermi surface related to Tc decrease.

Abstract

The substitution of gallium by aluminum, germanium, tin and indium in PuCoGa5, the actinide-based superconductor with the highest critical temperature, has been investigated. Only systems with 20% substitution by Al and Ge (i.e. PuCoGa4Al and PuCoGa4Ge) have been successfully synthesized by annealing arc-melted samples. X-ray powder diffraction refinements indicate an enhanced c/a ratio in these two compounds but the magnetic susceptibility measurements reveal a large reduction of the critical temperature Tc compared to PuCoGa5. DFT+ED calculations indicate significant changes in the Fermi surface, probably related to the decrease of Tc, in these compounds. In addition, the isotopic effect of the atomic mass of gallium, using 69Ga and 71Ga isotopes, was also investigated without observable influence on the critical temperature of PuCoGa5.