Theoretical approach to ground states of the ν=2/3 bilayer fractional quantum Hall systems

► New discovery of basic features of ground states in ν=2/3 bilayer fractional quantum Hall systems. ► Phase diagrams of ν=2/3 systems in the ΔSAS-ΔZ plane presented for the first time. ► Exact-diagonalization (ED) calculations and analysis of an exactly solvable model. ► The low-lying energy spectra of ν=2/3 systems for various values of d, ΔSAS and ΔZ. ► ΔSAS and d dependences of energy gaps between lowest two eigenstates in ν=2/3 systems.