Quantum phase diagram of the frustrated spin ladder with next-nearest-neighbor interactions

Abstract

Using the density matrix renormalization group technique, we investigate the quantum phase diagram of a ferromagnetic frustrated twoleg spin-1/2 ladder with diagonal and in-chain next-nearest-neighbor (NNN) interactions. By analyzing the correlation function and four-site entropy, we obtain the quantum phase diagram of the system. We find that the system possesses a tetramer phase, a ferromagnetic phase and states I and II. Spin arrangements for states I and II are also determined. In addition, the influence of the in-chain NNN interaction J 2 on the phase transitions of the antiferromagnetic case is studied. We show the phase diagram and find that the stagger dimer phase exists only in a narrow parameter region. Meanwhile, the existence of the controversial columnar dimer phase at J 2 = 0 is arefully analyzed. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.