open access

https://hdl.handle.net/2115/53438

C-13 NMR study of commensurate antiferromagnetism in (TMTTF)(2)Br

英語

2013-09-12

Amer physical soc

Physical review b

88(12)

125121-1-125121-6

Quasi-one-dimensional organic conductors (TMTCF)(2)X have various electric and magnetic properties. Although theoretical and experimental studies have suggested that (TMTTF)(2)Br has the properties of commensurate antiferromagnetism, details of the magnetic structure of this compound are unclear. Two types of antiferromagnetism are expected, one due to a localized electron and the other to the nesting of the Fermi surface. We therefore assessed the antiferromagnetic structure of (TMTTF)(2)Br using C-13 NMR. Site assignment of the observed antiferromagnetic spectrum confirmed that there were two magnetic molecular sites, with staggered moments and amplitude of 0.11 mu(B)/molecule, as well as nonmagnetic molecular sites. A commensurate structure with antiferromagnetic ordering of (up arrow omicron down arrow omicron) along a one-dimensional chain would be expected as the freezing of antiferromagnetic fluctuations in the charge-ordered phase of the (TMTTF)(2)AsF6 salt. The presence of a nodal site is strongly suggestive of the nesting type antiferromagnetism. The fine structure of the antiferromagnetic spectrum suggests superlattice along the interchain direction. We could not observe line broadening due to the charge order above the antiferromagnetic transition.

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©2013 American Physical Society

1098-0121