Jahn-Teller induced Davydov splitting in TbVO4

Abstract
Far-infrared absorption spectroscopy has revealed the presence of a strong absorption line at 38 cm-1 in the Jahn-Teller distorted phase of TbVO4. The fact that this is at a lower energy than any previous observations would indicate, is attributed to a Davydov splitting caused by coupling to odd-parity phonons. The temperature dependence and the splitting of this line in a magnetic field are also reported. The construction of a Hamiltonian incorporating this odd-parity coupling is discussed and solutions are found using Green function techniques.