2004/01/31 by D. N. Aristov, M. N. Kiselev
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.70.224402
published as Phys.Rev. B 70, 224402 (2004) · 12 pages, 4 figures
arxiv created 2004/10/13 · arxiv updated 2009/12/01
We study two similar spin ladder systems with the ferromagnetic leg coupling. First model includes two sorts of spins, s= 1/2 and s= 1, and the second model comprises only s=1/2 legs coupled by a "triangular" rung exchange. The antiferromagnetic (AF) rung coupling destroys the long-range order and eventually makes the systems equivalent to the AF s=1/2 Heisenberg chain. We investigate the situation by different methods in weak and strong rung coupling limits. Particularly we compare the spin-wave theory and the bosonization method in the weak coupling regime of the second model. We analyze the spectra and correlations, and discuss the order parameter of these ladder systems.