Metal-Insulator-Superconductor Transition in Two-Channel Interacting Many-Body Systems

Using a slave-rotor approach within a mean-field theory, we study two-channel interacting systems to investigate the competition of metallic, Mott-insulating, and superconducting phases. Considering spin-3/2 cold atoms on optical lattices as a model system and treating a spin-3/2 atom as a bound state of a charge and a spin, we uncover a novel form of matter due to the competition between metal and superconducting phase. This novel unconventional phase emerges as a result of the global U(1) broken symmetries with respect to both roton and spinon fields. Further, we argue that the emergence of this unconventional phase is a generic phenomenon associates with many body systems where there are competing interactions. As such, we show that this unconventional phase can exist in rubidium doped fullerides under pressure.