Strongly interacting phonons and orbital excitations are observed in the same energy range for CuSb2O6, unlocking a so-far unexplored type of electron-phonon interaction. An orbital wave at ∼550 cm−1 softens on warming and strongly interferes with a phonon at ∼500 cm−1, giving rise to a merged excitation of mixed character. An electronic continuum grows on warming to the orbital ordering temperature TOO=400 K, generating an important phonon decay channel. This direct and simultaneous observation of orbital and vibrational excitations reveals details of their combined dynamics. In addition, phonon frequency anomalies due to magnetic correlations are observed below ∼150 K, much above the three-dimensional magnetic ordering temperature TN3D=8.5 K, confirming one-dimensional magnetic correlations along Cu-O-O-Cu linear chains in the paramagnetic state.
@article{arxiv.1803.00559,
title = {Coupling of phonons with orbital dynamics and magnetism in CuSb$_2$O$_6$},
author = {D. T. Maimone and A. B. Christian and J. J. Neumeier and E. Granado},
journal= {arXiv preprint arXiv:1803.00559},
year = {2018}
}