Spin-Peierls instability in the spin- 1∕2 Heisenberg three-leg ladder
Mohamed Moussadek Azzouz, Khalada Shahin, Gennady Y. Chitov
Because the three-leg ladder behaves like a renormalized single Heisenberg chain, we argue that a spin-Peierls instability must occur in this system when it is coupled to three-dimensional phonons. Using the bond-mean-field theory, we show that this is indeed the case. The dimerized state below the spin-Peierls transition temperature forms into the columnar dimerized phase instead of the staggered one. This contrasts with the argument based on antiferromagnetism. A physical argument based rather on spin bonding into singlets could explain why the columnar configuration is favored. No quantum criticality (gaplessness) can occur in the columnar arrangement of the dimerized chains.
arXiv:0708.4181•Physical Review B•Oct 26, 2007•20 citations