Predicting New Heavy Fermion Materials within Carbon-Boron Clathrate Structures

Heavy fermion materials have been a rich playground for strongly correlated physics for decades. However, engineering tunable and synthesizable heavy fermion materials remains a challenge. We strive to integrate heavy fermion properties into carbon boron clathrates as a universal structure which can host a diverse array of interesting physical phenomena. Using a combination of density functional theory and dynamical mean field theory, we study two rare earth carbon boron clathrates, SmB$_3$C$_3$ and CeB$_3$C$_3$, and explore properties arising from the strong electronic correlations. We find a significant increase in the density of states at the Fermi level in CeB$_3$C$_3$ as the temperature is lowered, indicating the development of a heavy electron state. In SmB$_3$C$_3$, a potential Kondo insulating state is identified. Both findings point to rare earth carbon boron clathrates as novel strongly correlated materials within a universally tunable structure, offering a fresh platform to innovate upon conventional heavy-fermion materials design.