Composite spin liquid in a correlated topological insulator: Spin liquid without spin-charge separation

In this paper, we present an alternative type of insulator, namely composite spin liquid, which can be regarded as a short-range B-type topological spin-density wave as proposed by J. He et al. [Phys. Rev. B 84, 035127 (2011)]. Composite spin liquid is a topological ordered state beyond the classification of traditional spin liquid states. The elementary excitations are the ``composite electrons'' with both spin and charge degrees of freedom, together with topological spin texture. This topological state supports the chiral edge mode but no topological degeneracy.