Berlin 2005 – scientific programme
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MA: Magnetismus
MA 14: Molekularer Magnetismus
MA 14.6: Talk
Saturday, March 5, 2005, 15:00–15:15, TU H1012
Hysteresis and Metastability of the Antiferromagnetic Heisenberg Spin-Icosahedron — •Christian Schröder1,2, Heinz-Jürgen Schmidt3, Jürgen Schnack3 und Marshall Luban2 — 1University of Applied Sciences Bielefeld, Dept. of Electrical Engineering and Computer Engineering, Bielefeld, Germany — 2Ames Laboratory & Iowa State University, Dept. of Physics, Ames, Iowa, USA — 3University of Osnabrück, Dept. of Physics, Osnabrück, Germany
Mounting on the vertices of an icosahedron classical or quantum spins that interact via nearest-neighbor isotropic antiferromagnetic Heisenberg exchange one generates a system that exhibits surprising physical properties when it is placed in an external magnetic field. At T=0 K the classical system undergoes an abrupt magnetic transition at a critical field Bcrit reminiscent of a first order phase transition. Moreover, this system shows hysteresis effects and metastabilty with an infinite lifetime at T=0 K and a characteristic lifetime distribution for finite T. These properties of the spin-icosahedron may also be of interest for potential applications in the area of nanomagnetic switches. Here, we present a full analytical description of the classical behavior for T=0 K and discuss finite temperature results from numerical quantum and classical calculations.