Structural correlations in $Cs_2CuCl_4$: Pressure dependence of electronic structures

  • Enrique Jara Universidad de Cantabria
  • Jose Antonio Barreda-Argüeso Universidad de Cantabria
  • Jesus Antonio González Universidad de Cantabria
  • Rafael Valiente Universidad de Cantabria
  • Fernando Rodriguez Universidad de Cantabria
Keywords: Cs2CuCl4; electronic structure; high pressure; band gap

Abstract

We have investigated the crystal structure of $Cs_2CuCl_4$ in the 0-20 GPa range as a function of pressure and how pressure affects its electronic properties by means of optical absorption spectroscopy. In particular, we focused on the electronic properties in the low-pressure Pnma phase, which are mainly related to the tetrahedral $CuCl_4^{2-}$ units distorted by the Jahn-Teller effect. This study provides a complete characterization of the electronic structure of $Cs_2CuCl_4$ in the Pmna phase as a function of the cell volume and the $Cu-Cl$ bond length, $R_{Cu-Cl}$. Interestingly, the opposite shift of the charge-transfer band-gap and the $Cu^{2+}$ d-d crystal-field band shift with pressure are responsible for the strong piezochromism of $Cs_2CuCl_4$. We have also explored the high-pressure structure of $Cs_2CuCl_4$ above 4.9 GPa yielding structural transformations that are probably associated with a change of coordination around $Cu^{2+}$. Since the high-pressure phase appears largely amorphized, any structural information from X-ray diffraction is ruled out. We use electronic probes to get structural information of the high-pressure phase.

Edited by: A. Goñi, A. Cantarero, J. S. Reparaz

Published
2019-06-21
How to Cite
Jara, E., Barreda-Argüeso, J. A., González, J. A., Valiente, R., & Rodriguez, F. (2019). Structural correlations in $Cs_2CuCl_4$: Pressure dependence of electronic structures. Papers in Physics, 11, 110004. https://doi.org/10.4279/pip.110004
Section
Articles