Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 39: Micro- and Nanostructured Magnetic Materials I

MA 39.7: Vortrag

Donnerstag, 29. März 2012, 11:00–11:15, EB 202

Formation of spin-spiral states in Fe zig-zag chains and ladders: A first principles study — •Muhammad Tanveer, Pedro Ruiz-Díaz, and Gustavo Pastor — Institut für Theoretische Physik, Universität Kassel, Heinrich Plett Straße 40, 34132 Kassel, Germany.

A first-principles study of the stability of spiral spin-density wave (SDW) states in free standing Fe wires having linear, zig-zag and ladder geometries is presented. The calculations are based on density-functional theory in the generalised gradient approximation. The spin-spiral magnetic arrangement is described by the wave vector q= (0, 0, q)2π/a along the chains axis. The stability of the spiral structure is quantified in terms of the total energy difference as a function of q and for different nearest-neighbor (NN) distances. We observed that the zigzag chains have a ferromagnetic (FM) stable ground state whilst the ladders chains tend to favour the formation of a spiral SDW with wave vector q ≅ (0, 0, 0.2)2π/a. The dependence of the local magnetic moments as a function of q reflects the itinerant character of magnetism in the Fe chains. The magnetic order and its stability as a function of the NN distances are interpreted in terms of the effective exchange-interaction parameters J_ij, which are derived in the framework of a phenomenological classical Heisenberg model.