Abstract
We have measured the magnetic susceptibilities of single crystals of with extremely low Zn concentration lower than at very low temperatures to investigate the spin-Peierls and antiferromagnetic transitions. The results show that the undoped has no antiferromagnetic phase down to 12 mK and there exists an antiferromagnetic long-range order with the easy axis along the axis for down to The minimum observed Néel temperature was 0.0285 K for the sample. From the concentration dependence of the Néel temperature it is concluded that there is no critical concentration for the occurrence of the antiferromagnetic long-range order. This indicates that the dimerization sustains the coherence of the antiferromagnetic phase of the spin polarization in impurity-doped systems and is consistent with the theory of the impurity-doped spin-Peierls system. The temperature dependence of the susceptibilities at of all samples indicates that the magnetic correlations between localized spins are enhanced by a relatively large interchain interaction of
- Received 24 March 1998
DOI:https://doi.org/10.1103/PhysRevB.58.R575
©1998 American Physical Society