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Correlations and Néel Order of Randomly Diluted Quantum Spin Ladders

M. Greven·R. J. Birgeneau
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Abstract

We present a Monte Carlo study of the correlation length $ξ$ of randomly diluted antiferromagnetic Heisenberg ladders, composed of two spin--1/2 chains. For weak and intermediate inter--chain couplings, $J_{\bot}/J \leq 1$, we find an enhancement of correlations that is strongest for a fraction $z^* \approx J_{\bot}/(8J)$ of dilutants. We are able to access the experimentally relevant low--temperature regime, $T/J \approx 1/500$, and find that the recently inferred Néel temperature of $Sr(Cu_{1-z}Zn_z)_2O_3$ corresponds to a curve of constant correlation length $ξ\approx 18$ of the single diluted ladder with $J_{\bot}/J \alt 1/2$. The primary reason for the Néel ordering is argued to be a strong enhancement of two--dimensional correlations due to a Cu--Sr--Cu exchange coupling of $\approx 10 meV$ in the stacking direction of the ladders.

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M. Greven, R. J. Birgeneau. 1998-03-05. Correlations and Néel Order of Randomly Diluted Quantum Spin Ladders. https://doi.org/10.1103/physrevlett.81.1945

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