We show strong numerical evidence in favor of an unexpected virtually gapless spectrum, with edge states localized at the boundaries, in frustrated spin-1/2 antiferromagnetic ladders with an odd number of legs. These features can be accurately reproduced by using a projected BCS wave function with a non-trivial pairing, that mixes even and odd reflection symmetries. This approach gives the correct classification of the excitations and provides a simple and very appealing picture of an unconventional spin-liquid phase stabilized by frustration.
Cite
@article{arxiv.cond-mat/0701658,
title = {Exotic gapless spectrum induced by frustration in quantum antiferromagnets},
author = {Federico Becca and Luca Capriotti and Alberto Parola and Sandro Sorella},
journal= {arXiv preprint arXiv:cond-mat/0701658},
year = {2009}
}