Phase Transitions in Staggered Spin Ladders
Abstract
We map spin ladders with nl legs and couplings J' across all rungs and J\(1+/-γ\) along the legs, staggered in both directions, to a sigma model. Setting its θ = \(2m+1\)π (where it is known to be gapless), we locate the critical curves in the γ versus J'/J plane at each nl, and spin S. The phase diagram is rich and has some surprises: When two gapped chains are suitably coupled, the combination becomes gapless. With nl, γ, and J'/J to control, the prospects for experimentally observing any one of these equivalent transitions are enhanced. We interpret our results in the framework of the resonating valence bond description of ladders.
- Publication:
-
Physical Review Letters
- Pub Date:
- October 1996
- DOI:
- 10.1103/PhysRevLett.77.3443
- Bibcode:
- 1996PhRvL..77.3443M