This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerized phase, which exists in a narrow parameter region of the so-called ~/1 - J2 model, vanishes if the interchain frustration is weak and anisotropic. Therefore, it concludes that the frustrating interaction indeed plays an important role in producing such a phase. As a complementary to our previous investigation, it reaches a more complete picture of the quantum phase transition in the frustrated spin ladder systems.
In the present paper,we study the effect of element substitution for quarter-filled nanoclusters of perovskite manganite by introducing Jahn-Teller type of perturbation interaction to the double-exchange Hamiltonian.Using the unrestricted real-space Hartree-Fock approximation method we find that,the Jahn-Teller electron-phonon interaction plays the central role in producing the phase transition from ferromagnetic phase to CE type antiferromagnetic phase.Not only the Jahn-Teller interaction benefits antiferromagnetic correlation,it also increases the charge density order parameter.These theoretical results provide a guidance to predict the properties and modify the composition of particles of perovskite manganite under nano-scale.
WANG HaiLongWANG RongMingWANG YuGangTIAN GuangShan
