TY - JOUR AU - Jara, Enrique AU - Barreda-Argüeso, Jose Antonio AU - González, Jesus Antonio AU - Valiente, Rafael AU - Rodriguez, Fernando PY - 2019/06/21 Y2 - 2024/03/28 TI - Structural correlations in $Cs_2CuCl_4$: Pressure dependence of electronic structures JF - Papers in Physics JA - Pap. Phys. VL - 11 IS - SE - Articles DO - 10.4279/pip.110004 UR - https://www.papersinphysics.org/papersinphysics/article/view/482 SP - 110004 AB - <p>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&nbsp;absorption spectroscopy. In particular, we focused on the electronic properties in the low-pressure&nbsp;<em>Pnma&nbsp;</em>phase, which are mainly related to the tetrahedral $CuCl_4^{2-}$ units distorted&nbsp;by the Jahn-Teller effect. This study provides a complete characterization of the&nbsp;electronic structure of $Cs_2CuCl_4$ in the&nbsp;<em>Pmna&nbsp;</em>phase as a function of the cell volume and&nbsp;the $Cu-Cl$ bond length, $R_{Cu-Cl}$. Interestingly, the opposite shift of the charge-transfer&nbsp;band-gap and the $Cu^{2+}$ <em>d-d&nbsp;</em>crystal-field band shift with pressure are responsible for the&nbsp;strong piezochromism of $Cs_2CuCl_4$. We have also explored the high-pressure structure of&nbsp;$Cs_2CuCl_4$ above 4.9 GPa yielding structural transformations that are probably associated&nbsp;with a change of coordination around $Cu^{2+}$. Since the high-pressure phase appears largely&nbsp;amorphized, any structural information from X-ray diffraction is ruled out. We use&nbsp;electronic probes to get structural information of the high-pressure phase.</p><p><strong>Edited by:</strong> A. Goñi, A. Cantarero, J. S. Reparaz</p> ER -