Micro‐Raman study of orbiton–phonon coupling in YbVO3

First‐order and multiphonon Raman active excitations are studied in YbVO₃ as a function of temperature in the orthorhombic and monoclinic phases. Below T ≃ 170 K, a G‐type orbital ordering with a concomitant monoclinic transition occurs. They enhance the phonon polarizabilities, allowing the resolution of room‐temperature bands, and activate new excitations around 700 cm⁻¹. Below T ∼ 65 K, the 700 cm⁻¹ excitations disappear, indicating a C‐type orbital ordering and a return to the orthorhombic structure. The observed phonon combinations around 1400 cm⁻¹ with a dominant Jahn‐Teller vibration at ∼690 cm⁻¹ reflect a possible orbiton‐phonon coupling. Copyright © 2011 John Wiley & Sons, Ltd.