Regensburg 1998 – wissenschaftliches Programm

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AM: Magnetismus

AM 11: Postersitzung

AM 11.17: Poster

Dienstag, 24. März 1998, 16:15–20:00, B

From one to two dimensions in quantum spin systems — •Mu-Sung Yang, Andreas Fledderjohann, Karl-Heinz Mütter, and Michael Karbach — Physics Department, University of Wuppertal, D-42097 Wuppertal, Germany

We study the first derivative of the staggered magnetization squared dm^†(θ)²/dθ and the second derivative d²e₀(θ)/dθ² of the ground state energy per site. The parameter θ controls the anisotropy between horizontal and vertical couplings in a two-dimensional (2D) spin-1/2 antiferromagnetic Heisenberg model. It is shown, that both derivatives diverge at θ=1, where the anisotropic 2D model reduces to the 1D model.