Abstract
We have performed a comprehensive investigation on the spin susceptibility of the organic quantum-spin systems (TMTTF) (, AsF, BF, ReO, and SCN) in the temperature range from up to 380 K. At elevated temperatures, the spin susceptibility at constant volume ( can be described by a spin- antiferromagnetic Heisenberg chain with exchange constants between 400 and 460 K. Below K, slight deviations from the model occur due to interchain interaction. At low temperatures, the compounds undergo transitions to various ordered states of structural or magnetic origin that are discussed in detail. The spin-dimerized ground states of (TMTTF)AsF and (TMTTF)BF can be described by an alternating spin chain with a singlet-triplet energy gap and 52 K, respectively. In (TMTTF)ReO, however, the spin susceptibility in the anion-ordered state deviates from this model and obeys an activated law with K. In the antiferromagnetic ground states of (TMTTF)SbF and (TMTTF)SCN an increase of the spin susceptibility is observed at the lowest temperatures.
1 More- Received 12 September 2010
DOI:https://doi.org/10.1103/PhysRevB.83.205126
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