TITLE: Orbital interaction analysis of cooperative Jahn-Teller distortion, charge/orbital/spin ordering, and spin exchange interactions in magnetic solids

SPEAKER: Professor M. -H. Whangbo,

TIME: Thursday Oct. 11, 2001 at 4 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

This talk provides a brief review on how to think about the spin exchange interactions in magnetic solids. We discuss the magnetic properties of various compounds such as Cu₄O₃, Ba₂Cu₃O₄C_l2, Ca_3.1Cu_0.9RuO₆, Ca₃Co₂O₆ and BaVS₃ from the viewpoint of spin orbital interaction energy. We examine the phenomena of cooperative Jahn-Teller distortion, orbital ordering and spin exchange in cubic perovskites KCuF₃, LaMnO₃ and YVO₃ from the viewpoint of orbital interactions between adjacent spin sites. We probe why LaMnO₃ undergoes a Jahn-Teller distortion but its analog CaFeO₃ undergoes a charge disproportionation.