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On the estimate of the spin-gap in quasi-1D Heisenberg antiferromagnets from nuclear spin-lattice relaxation

R. Melzi·P. Carretta
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Abstract

We present a careful analysis of the temperature dependence of the nuclear spin-lattice relaxation rate $1/T_1$ in gapped quasi-1D Heisenberg antiferromagnets. It is found that in order to estimate the value of the gap correctly from $1/T_1$ the peculiar features of the dispersion curve for the triplet excitations must be taken into account. The temperature dependence of $1/T_1$ due to two-magnon processes, is reported for different values of the ratio $r=J_{\perp}/J_{\parallel}$ between the superexchange constants in a 2-leg-ladder. As an illustrative example we compare our results to the experimental findings for $^{63}Cu 1/T_1$ in the dimerized chains and 2-leg-ladders contained in Sr$_{14}Cu_{24}O_{41}$

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R. Melzi, P. Carretta. 1999-04-06. On the estimate of the spin-gap in quasi-1D Heisenberg antiferromagnets from nuclear spin-lattice relaxation. https://arxiv.org/abs/cond-mat/9904074

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