Structural phase transition in two-dimensional kagomé antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide·BF 4·1/3 (acetone)

Takashi Kambe, Yoshio Nogami, Kokichi Oshima, Wataru Fujita, Kunio Awaga

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We found for the first time a structural phase transition in two-dimensional kagomé antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide (m-MPYNN)·BF4·1/3 (acetone). As, below Ts = 128.7 K, the intense satellite reflections are clearly observed at the modulation wave vector of qs = (1/3,1/3,0), the unit cell of the low-temperature phase is enlarged to √3a × √3a × c. In the low-temperature phase, the space group is determined to be P31c. The orientation of acetone molecules orders below Ts, leading to the lack of the three-fold axis. To confirm whether the low-temperature phase maintains a kagomé-like network structure or not, we estimate the overlap integrals between the singly occupied molecular orbital wave functions of the MPYNN molecules by the extended Hückel method. The result is that all the overlap integrals are modified below Ts, suggesting that the system below Ts cannot be regarded as the uniform S = 1 kagomé antiferromagnet.

Original languageEnglish
Pages (from-to)796-799
Number of pages4
JournalJournal of the Physical Society of Japan
Volume73
Issue number4
DOIs
Publication statusPublished - Apr 2004

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acetone
molecules
molecular orbitals
wave functions
modulation
estimates
cells

Keywords

  • Kagomé lattice, m-MPYNN·BF ·1/3(acetone)
  • Structural phase transition
  • X-ray diffraction

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Structural phase transition in two-dimensional kagomé antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide·BF 4·1/3 (acetone). / Kambe, Takashi; Nogami, Yoshio; Oshima, Kokichi; Fujita, Wataru; Awaga, Kunio.

In: Journal of the Physical Society of Japan, Vol. 73, No. 4, 04.2004, p. 796-799.

Research output: Contribution to journalArticle

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abstract = "We found for the first time a structural phase transition in two-dimensional kagom{\'e} antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide (m-MPYNN)·BF4·1/3 (acetone). As, below Ts = 128.7 K, the intense satellite reflections are clearly observed at the modulation wave vector of qs = (1/3,1/3,0), the unit cell of the low-temperature phase is enlarged to √3a × √3a × c. In the low-temperature phase, the space group is determined to be P31c. The orientation of acetone molecules orders below Ts, leading to the lack of the three-fold axis. To confirm whether the low-temperature phase maintains a kagom{\'e}-like network structure or not, we estimate the overlap integrals between the singly occupied molecular orbital wave functions of the MPYNN molecules by the extended H{\"u}ckel method. The result is that all the overlap integrals are modified below Ts, suggesting that the system below Ts cannot be regarded as the uniform S = 1 kagom{\'e} antiferromagnet.",
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T1 - Structural phase transition in two-dimensional kagomé antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide·BF 4·1/3 (acetone)

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N2 - We found for the first time a structural phase transition in two-dimensional kagomé antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide (m-MPYNN)·BF4·1/3 (acetone). As, below Ts = 128.7 K, the intense satellite reflections are clearly observed at the modulation wave vector of qs = (1/3,1/3,0), the unit cell of the low-temperature phase is enlarged to √3a × √3a × c. In the low-temperature phase, the space group is determined to be P31c. The orientation of acetone molecules orders below Ts, leading to the lack of the three-fold axis. To confirm whether the low-temperature phase maintains a kagomé-like network structure or not, we estimate the overlap integrals between the singly occupied molecular orbital wave functions of the MPYNN molecules by the extended Hückel method. The result is that all the overlap integrals are modified below Ts, suggesting that the system below Ts cannot be regarded as the uniform S = 1 kagomé antiferromagnet.

AB - We found for the first time a structural phase transition in two-dimensional kagomé antiferromagnet m-N-methylpyridinium α-nitronyl nitroxide (m-MPYNN)·BF4·1/3 (acetone). As, below Ts = 128.7 K, the intense satellite reflections are clearly observed at the modulation wave vector of qs = (1/3,1/3,0), the unit cell of the low-temperature phase is enlarged to √3a × √3a × c. In the low-temperature phase, the space group is determined to be P31c. The orientation of acetone molecules orders below Ts, leading to the lack of the three-fold axis. To confirm whether the low-temperature phase maintains a kagomé-like network structure or not, we estimate the overlap integrals between the singly occupied molecular orbital wave functions of the MPYNN molecules by the extended Hückel method. The result is that all the overlap integrals are modified below Ts, suggesting that the system below Ts cannot be regarded as the uniform S = 1 kagomé antiferromagnet.

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