Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 46: MagneticThin Films II

MA 46.6: Vortrag

Donnerstag, 29. März 2012, 16:15–16:30, EB 202

Novel orbital ordering and Raman modes in 2p magnetic CsO2 — •baomin zhang¹, s. riyadi², t. t. m. palstra², g. a. de wijs¹, r. a. de groot¹, and g. r. blake² — ¹Electronic Structure of Materials, Institute of Molecules and Materials, Radboud University Nijmegen — ²Solid State Materials for Electronics, Zernike Institute for Advanced Materials, Rijksuniversity Groningen

Aniogenic magnetism is a relatively new area recently. Antiferromagnetic CsO2 has a tetragonal stucture above 190 K, and the symmetry is reduced (accompanied by the tilting of oxygen dimers) at lower temperatures. Based on density functional calculation, we report a novel orbital ordering here, which is new in 2p magnetic materials. The highest occupied orbitals show ordered py and px characters, and the strong super exhange interaction between px and py orbitals realizes the one dimensional spin chain character found in experiments. Also, the calculated Raman frequencies 1118 cm-1 (streching of oxygen dimer), 195---200cm-1 (libration of dimer) and 66--75 cm-1 (exclusive movement of Cs along lattice c direction) agree well with experiments. The interpretation for latter two cases is given for the first time.