Frustrated three-leg spin tubes: From spin1∕2with chirality to spin3∕2

Motivated by the recent discovery of the spin tube [(CuCl2tachH)3Cl]Cl2, we investigate the properties of a frustrated three-leg spin tube with antiferromagnetic intra- 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 whole gapped phase and slightly beyond. The implications for [(CuCl2tachH)3Cl]Cl2 are discussed, with the conclusion that this system behaves essentially as a spin-3∕2 chain.

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Physical Review B, 73, 1, 014409

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 Record created 2019-06-24, last modified 2020-04-20

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