Spin-Peierls transition in the charge-ordered organic conductor θ-BEDT-TTF2RbZn(SCN)4

Masashi Watanabe, Yukio Noda, Yoshio Nogami, Hatsumi Mori

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9 Citations (Scopus)

Abstract

X-ray investigation of θ-BEDT-TTF2RbZn(SCN)4 was carried out around the temperature of the phase transition to the nonmagnetic state. θ-BEDT-TTF2RbZn(SCN)4 exhibits a metal-insulator transition accompanied by a charge ordering at TCO = 200 K. In the one-dimensional spin chain formed by this charge ordering, BEDT-TTF donor molecules are aligned uniformly along the a-axis obeying the 21 screw symmetry of the space group P212 121 below TCO. At the ground state, the system becomes nonmagnetic. The transition temperature Tc to the nonmagnetic phase seems to scatter around 20K and may depend on the sample. We found that the extinction rule of [h00: h = 2n] no longer applied below approximately 20 K. This indicated a symmetry breaking of the 21 screw symmetry along the a-axis in the nonmagnetic state. The observed peak intensities violating the extinction rule were about 10-4 of other general Bragg reflection peak intensities. This structural change should be interpreted as a spin-Peierls transition in the charge-ordered system. In addition, a corresponding anomaly was observed in the lattice parameter a.

Original languageEnglish
Article number124602
Journaljournal of the physical society of japan
Volume76
Issue number12
DOIs
Publication statusPublished - Dec 1 2007

Keywords

  • BEDT-TTF
  • Charge order
  • Organic conductor
  • Spin-Peierls transition
  • X-ray diffraction

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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