hide
Free keywords:
-
Abstract:
The coupling of charge, lattice, orbital, and spin degrees of freedom
was studied in a p-electron mixed-valence Cs4O6 compound by the electron
paramagnetic resonance (EPR) and Cs-133 nuclear magnetic resonance
(NMR). The dramatic differences in the evolution of the EPR and Cs-133
NMR spectra measured under different cooling protocols reveal two
competing low-temperature phases: quenched high-temperature cubic and
the low-temperature low-symmetry phases, respectively. They differ in
the orientation of O-2(-) anion axes, the ordering of p* molecular
orbitals, and the superexchange interactions through the Cs+ bridges.
The transformation between the two phases involves large amplitude
reorientations of O-2 groups and is extremely sluggish, thus explaining
the coexistence of both phases and the deviations of the magnetic
susceptibility from the simple Curie-Weiss dependence at low
temperatures.
