Two-leg spin ladders have a rich phase diagram if rung, diagonal, and plaquette couplings are allowed for. Among the possible phases there are two Haldane-type spin liquid phases without local order parameter, which differ, however, in the topology of the short range valence bonds. We show that these phases can be distinguished numerically by two different string order parameters. We also point out that long-range string and dimer orders can coexist.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Feb 26 2001|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics