Origin of the piezochromism in Cs2CuCl4: Electron-phonon and crystal-structure correlations

E. Jara, J. A. Barreda-Argüeso, J. González, F. Rodríguez, and R. Valiente
Phys. Rev. B 99, 134106 – Published 18 April 2019

Abstract

By using optical absorption and Raman spectroscopy, we have investigated the effects of pressure in the structural, electronic, and vibrational properties of Cs2CuCl4 in the 0–20 GPa range. Our study has provided a complete characterization of the electronic and vibrational structures of Cs2CuCl4 in the low-pressure Pnma phase as a function of cell volume and the Cu-Cl bond length, RCu-Cl. We have focused on the electronic structure in the Pnma phase, which is mainly related to the tetrahedral CuCl42 units distorted by the Jahn-Teller effect. The strong piezochromism of Cs2CuCl4 is caused by the opposite shift of the charge-transfer band gap and the Cu2+ d-d crystal-field transitions with pressure. The high-pressure structure of Cs2CuCl4 above 4.9 GPa yields structural transformations that we ascribe to a change of coordination around Cu2+. The high-pressure phase appears largely amorphized, therefore any structural information from x-ray diffraction is ruled out. Here we use electronic and vibrational probes to get inside the structural information.

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  • Received 30 January 2019
  • Revised 29 March 2019

DOI:https://doi.org/10.1103/PhysRevB.99.134106

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

E. Jara, J. A. Barreda-Argüeso, J. González, and F. Rodríguez*

  • MALTA TEAM, DCITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain

R. Valiente

  • Nanomedicine Group-IDIVAL, Dpto. Física Aplicada, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain

  • *fernando.rodriguez@unican.es

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Issue

Vol. 99, Iss. 13 — 1 April 2019

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