Frustrated three-leg spin tubes: from spin 1/2 with chirality to spin 3/2

Authors:
  • JFJ. -B. Fouet
    J. -B. Fouet
  • ALA. Laeuchli
    A. Laeuchli
  • SPS. Pilgram
    S. Pilgram
  • RNR. M. Noack
    R. M. Noack
  • FMF. Mila
    F. Mila
Preprint
Publisher website
Google Scholar
Abstract
Motivated by the recent discovery of the spin tube [(CuCl$_2$tachH)$_3$Cl]Cl$_2$, we investigate the properties of a frustrated three-leg spin tube with antiferromagnetic intra-ring and inter-ring couplings. We pay special attention to the evolution of the properties from weak to strong inter-ring coupling and show on the basis of extensive density matrix renormalization group and exact diagonalization calculations that the system undergoes a first-order phase transition between a dimerized gapped phase at weak coupling that can be described by the usual spin-chirality model and a gapless critical phase at strong coupling that can be described by an effective spin-3/2 model. We also show that there is a magnetization plateau at 1/3 in the gapped phase and slightly beyond. The implications for [(CuCl$_2$tachH)$_3$Cl]Cl$_2$ are discussed, with the conclusion that this system behaves essentially as a spin-3/2 chain.