First-order metal–semiconductor transition triggered by rattling transition in tetrahedrite Cu12Sb4S13: Cu-nuclear magnetic resonance studies

Takashi Matsui, Haruki Matsuno, Hisashi Kotegawa, Hideki Tou, Koichiro Suekuni, Takumi Hasegawa, Hiromi I. Tanaka, Toshiro Takabatake

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3 Citations (Scopus)


Tetrahedrite Cu12Sb4S13 shows a metal–semiconductor transition (MST) at TMST = 85 K. We have studied the mechanism of the MST by measurements of Cu-NMR. Above TMST, the Cu-NMR spectrum consists of signals from a tetrahedral Cu(1) 12d site and a trigonally coordinated Cu(2) 12e site. Analyses of the spectra at 95 and 20 K yield NMR and nuclear quadrupole resonance (NQR) parameters above and below TMST. The Cu(1) signal does not show clear quadrupole splitting, which remains unchanged on cooling across TMST. On the other hand, the Cu(2) signal at T > TMST clearly shows the quadrupole splitting characterized by a quadrupole frequency νQ(2) ≈ 18.6 MHz and an asymmetry parameter η(2) ≈ 0.03. Below TMST, the values of νQ(2) and η(2) change markedly. Such marked changes in NQR parameters provide evidence of a remarkable change in the local electronic structure around the Cu(2) site. Together with νQ from NMR spectra and that from first-principles calculation, we conclude that the Cu(2) atoms are displaced from the sulfur triangles below TMST. We also found that the NMR Knight shift and the spin–lattice relaxation rate divided by temperature, 1=T1T, for the Cu(1) signal markedly change below TMST, which is ascribable to the reduction in the electronic density of states at the Fermi level. We further discuss the relationship among the MST, structural transformation, and crystal structure below TMST

Original languageEnglish
Article number054710
Journaljournal of the physical society of japan
Issue number5
Publication statusPublished - 2019

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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