Pressure-driven change of ground state of Ce3Pd3Bi4 : A DFT+DMFT study

Abstract

A candidate material for strongly correlated topological materials, ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Bi}}_{4}$ has attracted much attention, but its ground state remains controversial. Compared with the typical Kondo insulator ${\mathrm{Ce}}_{3}{\mathrm{Pt}}_{3}{\mathrm{Bi}}_{4}$, two possibilities of ground states are proposed: ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Bi}}_{4}$ is either a spin--orbit-driven topological semimetal or a Kondo insulator with less Kondo coupling strength than platinum. Here, we performed density functional theory $(\mathrm{DFT})+\mathrm{dynamical}$ mean field theory (DMFT) calculations on ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Bi}}_{4}$ under different pressures to clarify its ground state, as pressure can tune the strength of Kondo coupling without affecting the strength of spin-orbit coupling. We found ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Bi}}_{4}$ has a metallic ground state and becomes insulating with increasing pressure at a low temperature. And as the pressure increased to 2 GPa, a hybridization energy gap can be observed at 10 K. As the pressure increased to 5 GPa, the electronic structure of ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Bi}}_{4}$ is even similar to that of the Kondo insulator ${\mathrm{Ce}}_{3}{\mathrm{Pt}}_{3}{\mathrm{Bi}}_{4}$ under ambient pressure, and a clear hybridization energy gap $(\ensuremath{\sim}3\phantom{\rule{0.28em}{0ex}}\mathrm{meV})$ appears at 20 K. Our results not only demonstrate that the key factor controlling the different ground states between the two compounds is Kondo physics, rather than spin-orbit coupling, but also confirm that ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Bi}}_{4}$ is an ideal material to tuning the ground states by changing the strength of hybridization by pressure.