Multiple quantum phase transitions of plutonium compounds

We show by quantum Monte Carlo simulations of realistic Kondo lattice models derived from electronic-structure calculations that multiple quantum critical points can be realized in plutonium-based materials. We place representative systems, including PuCoGa${}_5$, on a realistic Doniach phase diagram and identify the regions where the magnetically mediated superconductivity could occur. The solution of an inverse problem to restore the quasiparticle renormalization factor for $f$ electrons is shown to be sufficiently good to predict the trends among Sommerfeld coefficients and magnetism. A suggestion on the possible experimental verification for this scenario is given for PuAs.

Figure 1

Summary of our results for Pu-115’s on a realistic Doniach phase diagram. The realistic data point is indicated by the symbol on the line for each target material. The main panel shows the trend among Sommerfeld coefficients, and the inset shows the Néel temperatures.

Figure 2

Schematic summary of our magnetic phase diagrams for Pu compounds plotted on the $(t,T_{\mathrm{N}})$ plane, where $t\equiv (J_{\mathrm{K}}-J_{\mathrm{K},\mathrm{QCP}})/J_{\mathrm{K},\mathrm{QCP}}$ is the rescaled Kondo coupling, with $J_{\mathrm{K},\mathrm{QCP}}$ being the first QCP in (a) and the third QCP in (b).

Figure 3

Analog of Doniach phase diagram for (a) Kondo temperature and (b) quasiparticle renormalization factors for PuCoGa${}_5$. The inset in (b) is a zoom-in picture around the first QCP with the vertical axis plotted in logarithm scale.