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Dimensional crossover in alternating spin chains

Adolfo E. Trumper·Claudio J. Gazza
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Abstract

The effect of antiferromagnetic interchain coupling in alternating spin (1,1/2) chains is studied by mean of spin wave theory and density matrix renormalization group(DMRG). Two limiting cases are investigated, the two-leg ladder and its two dimensional (2D) generalization. For the 2D case, spin wave approximation predicts a smooth dimensional crossover keeping the ground state ordered, whereas in the ladder case the DMRG results show a gapped ground state for any $J_{\perp}>0$. Furthermore, the behavior of the correlation functions closely resemble the uniform spin-1/2 ladder. However, for small $J_{\perp}$, the gap behaves quadratically as $Δ\sim0.6 J^2_{\perp}$. Similarly to uniform spin chains, it is conjectured an analogous spin gap behavior for an arbitrary number of mixed spin chains

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Adolfo E. Trumper, Claudio J. Gazza. 2001-09-10. Dimensional crossover in alternating spin chains. https://doi.org/10.1016/s0921-4526(02)00743-3

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