Low Energy Properties of Ferrimagnetic 2-leg Ladders: a Lanczos study

Abstract

We apply the Lanczos method to a 2-leg ladder with mixed spins of magnitudes $(S_1,S_2)=(1,1/2)$ located at alternating positions along the ladder. The effect of dimerization $\gamma$ is also considered according to two different patterns. A Spin Wave Theory (SWT) is applied to this model predicting one gapless branch with ferromagnetic properties and another gapful branch with antiferromagnetic nature as low energy excitations of the model. We compute the ground state energies, Ferro- and AF-excitation gaps, magnetizations and correlation functions as a function of $J^{\prime }$ and $\gamma$ which results into a fine estimate of the phase diagram. The Lanczos results are compared with the SWT analysis and a qualitative agreement is found but with numerical discrepancies. We also study numerically the Spin-Peierls instability and find that it is conditional for any value of $J^{\prime }\in (0,2)$ and both dimerization patterns.

REVTEX file, 9 pages, 1 Table, 9 eps Figures. Accepted in PRB

Cited by in corpus (10)

• Phase diagram of a frustrated mixed-spin ladder with diagonal exchange bonds
• Antiferromagnetically coupled alternating spin chains
• Magnetic properties and phase diagrams of the ferrimagnetic triangular nanotube with core-shell structure: A Monte Carlo study
• Nature of insulating state in NaV${}_2$O${}_5$ above charge-ordering transition: a cluster DMFT study
• Fractional magnetization plateaux of the spin-1/2 Heisenberg orthogonal-dimer chain revisited: strong-coupling approach developed from the exactly solved Ising-Heisenberg model
• Frustrated spin ladder with alternating spin-1 and spin-1/2 rungs
• Phase diagram of the XXZ ferrimagnetic spin-(1/2, 1) chain in the presence of transverse magnetic field
• Mixed-spin Heisenberg ladders in a magnetic field
• Magnetic phase diagram of a frustrated ferrimagnetic ladder: Relation to the one-dimensional boson Hubbard model
• Phase diagram of frustrated mixed-spin ladders in the strong-coupling limit