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Residual entropy and spin gap in a one-dimensional analog of the pyrochlore antiferromagnet

M. Mambrini·J. Trebosc·F. Mila
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Abstract

We show that the low-energy sector of the S=1/2, antiferromagnetic Heisenberg model on a one-dimensional lattice of coupled tetrahedra consists of 2^N replica of the spectrum of the dimerized Heisenberg chain, where N is the number of tetrahedra. This provides a proof of the following properties: i) there is a residual ground-state entropy per spin equal to 2^{1/4}; ii) there is a singlet-triplet gap as long as the coupling between the tetrahedra is smaller than the internal one. These properties are compared to available results on the pyrochlore lattice.

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M. Mambrini, J. Trebosc, F. Mila. 1998-12-15. Residual entropy and spin gap in a one-dimensional analog of the pyrochlore antiferromagnet. https://doi.org/10.1103/physrevb.59.13806

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