Anomalous spin dynamics and orbital excitations in Mott-insulating titanates

Abstract
Spin and orbital degrees of freedom play an important role in the various phenomena of strongly correlated electron systems like unconventional high-temperature superconductivity in cuprates or colossal magnetoresistance in manganates. Our extensive neutron scattering experiments on the cubic perovskite titanates LaTiO3 and YTiO3 lead to the discovery of a highly unusual magnetic ground state which is in contradiction to the standard Goodenough-Kanamori rules, but indicates the presence of strong orbital fluctuations [1-4]. Raman light scattering spectra of LaTiO3 and YTiO3 exhibit unexpected features in the high energy range well above the phonon spectrum [5]. Using momentum dependent resonant inelastic x-ray scattering (RIXS) experiments in combination with theoretical calculations, we were able to identify these excitations as collective orbital excitations (orbital waves termed ‘orbitons’) [6-7].
Description
Keywords
Spin, Dynamics, Excitation, Mott scattering, Titanates, Temperature range 0400-1000 K, Manganates, Scattering
Citation
Ulrich, C., Khaliullin, G., Ament, L. J. P., Ghiringhelli, G., Braicovich, L., Lorenz, T., Tokura, Y., van den Brink, J. & Keimer, B. (2010). Anomalous spin dynamics and orbital excitations in Mott-insulating titanates. Paper presented to the 34th Annual Condensed Matter and Materials Meeting 2010, Waiheke Island Resort, Waiheke, Auckland, New Zealand 2 - 5 February 2010. Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2010/