Regensburg 2002 – wissenschaftliches Programm

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MA: Magnetismus

MA 11: Molekularer Magnetismus

MA 11.2: Hauptvortrag

Mittwoch, 13. März 2002, 14:30–15:00, H22

Dimerized and frustrated quantum magnets — •Wolfram Brenig — Institut für Theoretische Physik, Technische Universität Braunschweig, 38106 Braunschweig

The search for supra-molecular magnetic materials has lead to the discovery of various novel compounds with localized magnetic moments arranged in chain, ladder, and depleted planar structures. Driven by the prospect of their technological relevance, the quantum magnetism of such systems has recently gained considerable interest revealing unconventional magnetic states and dynamical properties due to spin-alternation and dimensional confinement as well as dimerization and frustration of the magnetic exchange. Here we will review and report on the ground state and spin dynamics of dimerized and frustrated quantum magnets focusing in particular on spin ladders, tetrahedral cluster spin systems and highly frustrated planar magnets. Using a combination of bond-operator theory, exact diagonalization and high-order series expansion results will be discussed for the quantum phases, the elementary one- and two-particle excitations, magnetic bound-states, and optical as well as some transport properties. (Work supported by the DFG)