Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 16: Correlated Electrons: Low-dimensional Systems - Models 2

TT 16.11: Vortrag

Dienstag, 27. März 2012, 12:15–12:30, H 0104

Application of Valence Bond States to Nano-Sized Spin Clusters — •Maren Gysler, Nikolaos P. Konstantinidis, and Oliver Waldmann — Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany

The importance of understanding correlations in nano-sized spin clusters has risen in recent years with the availability of magnetic systems such as single-molecule magnets and spins attached to surfaces, which consist of a dozen or so antiferromagnetically coupled metal centers with potentially large spin lengths. Strong correlations between neighboring spins are difficult to single out when the familiar product basis or irreducible tensor operator techniques are used. The valence bond states can be used in an efficient way to study ground-state correlations of the clusters as strong short range quantum correlations can naturally be captured by them.

In this talk we will present a general method to use valence bond states as an alternative basis for the antiferromagnetic Heisenberg Hamiltonian of spin clusters with arbitrary exchange coupling strength, spins, and coupling topologies. The complications due to the overcompletness and non-orthogonality are circumvented by diagonalizing the Hamilton matrix in the spin coupled basis. Subsequently the spin coupled states are expressed in what we call the physical valence bond states. The developed method will be applied to special examples of spin clusters for illustration.