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<p>Layered chalcogenides like CuInP<sub>2</sub>S<sub>6</sub> are room temperature ferroelectrics. Modest compression even increases the electric polarization, raising questions about the origin of this unusual trend and other properties under pressure. In this work, we combine synchrotron-based infrared and Raman scattering spectroscopies, x-ray diffraction, and resistivity measurements with first-principles calculations of the lattice dynamics and energy landscape to unravel the influence of pressure on symmetry, polarization, and metallicity. We uncover a remarkable series of phase transitions across a series of polar space groups: monoclinic <i>C</i><i>c</i> → trigonal <i>P</i>31<i>c</i> (prismatic sulfur) → <i>P</i>31<i>c</i> (octahedral sulfur). True metallicity develops above 63 GPa, significantly higher than in related <i>M</i>PS<sub>3</sub> materials (<i>M</i> = Mn, Co, Fe, Ni), offering a picture of competing states of matter that is different than previously supposed. Detailed examination of pressure trends within the <i>C</i><i>c</i> phase also reveals phonon lifetime changes and streaking of satellite x-ray peaks that correlate with the maximum polarization. We discuss these tendencies in terms of Cu<sup>+</sup> ion migration, phase formation, and the overall energy landscape. Our findings place the high pressure behavior of CuInP<sub>2</sub>S<sub>6</sub> on a firm foundation and pave the way for the development of structure-property relations in this family of complex chalcogenides.</p>

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Pressure-tuned plethora of ferroelectric phases in CuInP2S6

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月17日

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  • Sambridhi Shah,
  • Pegah Mohammadi,
  • Bess G. Singidas,
  • Kevin A. Smith,
  • Yanhong Gu,
  • Luther J. Langston,
  • Brian Taylor,
  • Ryan P. Siebenaller,
  • Michael A. Susner,
  • Rahul Rao,
  • Sang-Wook Cheong,
  • Hirokazu Kadobayashi,
  • Roland V. Sarmago,
  • Zhenxian Liu,
  • Takahiro Matsuoka,
  • Sobhit Singh,
  • Janice L. Musfeldt

摘要

Layered chalcogenides like CuInP2S6 are room temperature ferroelectrics. Modest compression even increases the electric polarization, raising questions about the origin of this unusual trend and other properties under pressure. In this work, we combine synchrotron-based infrared and Raman scattering spectroscopies, x-ray diffraction, and resistivity measurements with first-principles calculations of the lattice dynamics and energy landscape to unravel the influence of pressure on symmetry, polarization, and metallicity. We uncover a remarkable series of phase transitions across a series of polar space groups: monoclinic Cc → trigonal P31c (prismatic sulfur) → P31c (octahedral sulfur). True metallicity develops above 63 GPa, significantly higher than in related MPS3 materials (M = Mn, Co, Fe, Ni), offering a picture of competing states of matter that is different than previously supposed. Detailed examination of pressure trends within the Cc phase also reveals phonon lifetime changes and streaking of satellite x-ray peaks that correlate with the maximum polarization. We discuss these tendencies in terms of Cu+ ion migration, phase formation, and the overall energy landscape. Our findings place the high pressure behavior of CuInP2S6 on a firm foundation and pave the way for the development of structure-property relations in this family of complex chalcogenides.