Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.52: Poster

Freitag, 26. März 2010, 11:00–14:00, Poster B1

Stability of ferromagnetic order in monoatomic transition-metal nanowires : A first-principles study of the effective exchange interactions between local moments — •Muhammad Tanveer, Pedro Ruiz Diaz, and Gustavo Pastor — Institut für Theoretische Physik, Universität Kassel, Heinrich Plett Straße 40, 34132 Kassel, Germany

A first principles study of the stability of the magnetism in transition-metal (TM) nanowires (NW) is presented. Constrained spin moment calculations of the effective exchange interactions between local moments in V, Fe and Co nanowires are performed in the framework of a generalized gradient approximation (GGA) to density-functional theory (DFT). In the case of V wires, ferromagnetic (FM) order is stable at the equillibrium nearest neighbor (NN) distance of the free standing wire. However, very small changes in the NN distance render FM order unstable. A transition from FM to spiral spin-density wave (SDW) order is found upon a contraction of about 1%. This remarkable result is interpreted in terms of the distance dependance of the effective exchange intractions J_ij between first, second, and third NN moments. Results are also given for the electronic density of states as a function of wave vector q of the spiral SDW state, which could be observed in STM experiments. Finally, the V results are contrasted with ongoing studies on Fe and Co wires.