Charge and Bonding in CuGeO<sub>3</sub> Nanorods.

O'Neal, Kenneth R; Al-Wahish, Amal; Li, Zhao-Qian; Dhalenne, Guy; Revcolevschi, Alexandre; Chen, Xue-Tai; Musfeldt, Janice L · Nano Lett · 2018

basic_science · Level V

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Abstract

We combine infrared and Raman spectroscopies to investigate finite length scale effects in CuGeO<sub>3</sub> nanorods. The infrared-active phonons display remarkably strong size dependence whereas the Raman-active features are, by comparison, nearly rigid. A splitting analysis of the Davydov pairs reveals complex changes in chemical bonding with rod length and temperature. Near the spin-Peierls transition, stronger intralayer bonding in the smallest rods indicates a more rigid lattice which helps to suppress the spin-Peierls transition. Taken together, these findings advance the understanding of size effects and collective phase transitions in low-dimensional oxides.