On metal-insulator transition in cubic fullerides

The interplay between degenerate orbital and electron correlation is a key to characterize the electronic phases in, for example, transition metal compounds [1,2] and alkali-doped fullerides [3]. Besides, the degenerate orbital couples to spin and lattice degrees of freedom ,giving rise to exotic phenomena. Here, we develop the self-consistent Gutzwiller approach for the simultaneous treatment of the Jahn-Teller effect and electron correlation, and apply the methodology to reveal the nature of the ground electronic state of fullerides [4]. For small Coulomb repulsion on site $U$, the fulleride is quasi degenerate correlated metal. With increase of $U$, we found the quantum phase transition from the metallic phase to JT split phase. In the latter, the Mott transition (MT) mainly develops in the half-filled subband, whereas the empty and the completely filled subbands are almost uninvolved. Therefore, we can qualify the metal-insulator transition in fullerides as an orbital selective MT [2] induced by JT effect. [1] Y. Tokura and N. Nagaosa, Science {\bf 288}, 462 (2000). [2] A. Koga, {\it et al.}, Phys. Rev. Lett. {\bf 92}, 216402 (2004). [3] O. Gunnarsson, Rev. Mod. Phys. {\bf 69}, 575 (1997). [4] N. Iwahara and L. F. Chibotaru, Phys. Rev. B {\bf 91}, 035109 (2015).