Observation of coupled 4f-electron-phonon excitations in the Van Vleck paramagnet TmES in high magnetic fields

Abstract

A model is proposed for explaining the anomalous behavior of the far-IR absorption spectra of the dielectric Van Vleck paramagnet thulium ethyl sulfate TmES. The good agreement obtained between the calculations and experiment on the basis of the idea of a resonance interaction between Tm3+ ions in one of the excited doublet states and optical phonons gives grounds for asserting that coupled 4f-electron-phonon excitations exist in TmES single crystals in high magnetic fields at liquid-helium temperatures. © 1998 American Institute of Physics.