Investigation of Vibronic Excitations in Ce2O3

Hybrid modes are often associated with quantum ground states and other novel emergent phenomena. One such hybrid mode, the vibronic mode, is a bound state between a crystal electric field (CEF) and a phonon. These modes, long predicted in systems where lattice vibrations significantly alter the CEF strength at a large moment spin site, are expected to precipitate unique spin-lattice coupling mechanisms. A recent Raman spectroscopy study revealed the emergence of two new modes below a purported antiferromagnetic transition at T=6.2K. These new modes were identified as vibronic excitations, though a thorough investigation of the CEF and phonon spectrum is required to strengthen this claim. For this reason, we seek to use MERLIN to map the evolution of CEF and phonon modes in Ce2O3 at temperatures both above and below the antiferromagnetic transition.