Density-wave instability in α−(BEDT-TTF)2KHg(SCN)4 studied by x-ray diffuse scattering and by first-principles calculations

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2010

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Mcode

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Language

en

Pages

1-14

Series

PHYSICAL REVIEW B, Volume 82, issue 13

Abstract

α−(BEDT-TTF)2KHg(SCN)4 develops a density wave ground state below 8 K whose origin is still debated. Here we report a combined x-ray diffuse scattering and first-principles density functional theory study supporting the charge density wave (CDW) scenario. In particular, we observe a triply incommensurate anharmonic lattice modulation with intralayer wave vector components which coincide within experimental errors to the maximum of the calculated Lindhard response function. A detailed study of the structural aspects of the modulation shows that the CDW instability in α−(BEDT-TTF)2KHg(SCN)4 is considerably more involved than those following a standard Peierls mechanism. We thus propose a microscopic mechanism where the CDW instability of the BEDT-TTF layer is triggered by the anion sublattice. Our mechanism also emphasizes the key role of the coupling of the BEDT-TTF and anion layers via the hydrogen bond network to set the global modulation.

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Keywords

density-wave, first principles, x-ray scattering

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Citation

Foury-Leylekian , P , Pouget , J-P , Lee , Y-J , Nieminen , R M , Ordejon , P & Canadell , E 2010 , ' Density-wave instability in α−(BEDT-TTF)2KHg(SCN)4 studied by x-ray diffuse scattering and by first-principles calculations ' , Physical Review B , vol. 82 , no. 13 , 134116 , pp. 1-14 . https://doi.org/10.1103/PhysRevB.82.134116