Title:  Ordering Due to Spin–Waves (AKA Order by Disorder)

Abstract:  Certain spin–systems, including some deemed to be of relevance to the question of orbital ordering in transition metal compounds are (mathematically) studied.  These systems have highly degenerate ground states characterized by a continuous symmetry.  Notwithstanding their infrared behavior, spin–wave excitations are shown to stabilize certain states (“order due to disorder”) and multiple phases are established.