In frustrated spin ladders composed of antiferromagnetically coupled chains, homogeneous or inhomogeneous, the interplay of frustration and correlations causes the emergence of two phases, Haldane (H) phase and rung singlet (RS) phase, in which the transition between these two phases had been under debate. In this paper we investigate the ground state phase diagram of frustrated mixed-spin-(1, 1/2) ladders, using the notions from quantum information theory such as entanglement entropy, Schmidt gap and entanglement levels degeneracies, and also defining various local and nonlocal order parameters. Employing two numerical techniques, the infinite time-evolving block decimation (iTEBD) and density matrix renormalization group (DMRG) algorithms, we obtain the ground state phase diagram of the ladder, and demonstrate that there is an intermediate phase between RS and H phases, where the ground state is disordered and the entanglement spectrum follow no particular pattern.
تحميل البحث