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Raies R. M. N. Dans les métaux organiques (TMTSF)₂PF₆ et (TMTSF)₂ClO₄ : incommensurabilité de l'onde de densité de Spin

Abstract : For the first time in the SDW state of the organic conductors (TMTSF)2PF6 and (TMTSF)2ClO4 the amplitude of the order parameter and the nesting vector are determined, from a detailed analysis of the methyl proton NMR line-shape for various magnetic field orientations. Il the paramagnetic metallic state, the fast rotational tunneling of the two un-equivalent methyl groups splits the line into one central line and two pairs of satellites with shifts depending on field orientation, in good agreement with theory. In the SDW state, the local fields due to the ordered magnetic structure lead to an important broadening of the line. By a careful analysis of the lineshape and its evolution in terms of field orientations, we prove, for both compounds, that the SDW is incommensurate; we are able to determine the local fields at each methyl site and separate the dipolar contribution from the hyperfine contact term; we deduce both the amplitude and wave vector of the SDW. The b* component of the nesting vector Qb (b* reciprocal lattice basis vector) for (TMTSF)2PF6 is in contradiction with simple theories leading to commensurate values (Qb=0 or Qb=0.5b*) but agrees with the consequences of realistic tight binding band calculations. The Q vector is different in (TMTSF)2ClO4 in agreement with the theoretical prediction that Q depends on the nature of anion and experimental conditions like pressure.
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https://hal-centralesupelec.archives-ouvertes.fr/tel-01330935
Contributor : Zeno Toffano <>
Submitted on : Monday, June 13, 2016 - 11:11:15 AM
Last modification on : Wednesday, September 16, 2020 - 4:46:21 PM

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  • HAL Id : tel-01330935, version 1

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Zeno Toffano. Raies R. M. N. Dans les métaux organiques (TMTSF)₂PF₆ et (TMTSF)₂ClO₄ : incommensurabilité de l'onde de densité de Spin . Supraconductivité [cond-mat.supr-con]. Université Paris Sud XI, 1985. Français. ⟨tel-01330935⟩

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