Phase separation in ν = 2/3 fractional quantum Hall systems

We study the ground state properties of the ν = 2/3 fractional quantum Hall systems basing on the density matrix renormalization group (DMRG) analysis. The ground-state energy and the pair correlation functions are calculated for various spin polarizations. The results indicate the phase separation in partially spin polarized states, where two domains of the spin unpolarized state and the fully spin polarized state are formed. We expect coupling with external degrees of freedom such as nuclear spins is important to realize multi-domain structures in partially spin polarized state.