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The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 5 Issue 3 (1998) pp 317-324
Effective Hamiltonians for holes in antiferromagnets: a new approach to implement forbidden double occupancy
W. Apel (1), H.-U. Everts (2), U. Körner (2) (a)
(1) Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
(2) Institut für Theoretische Physik, Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
Received: 23 December 1997 / Accepted: 17 March 1998
Abstract: A coherent state representation for the electrons of ordered antiferromagnets is used to derive effective Hamiltonians for the dynamics of holes in such systems. By an appropriate choice of these states, the constraint of forbidden double occupancy can be implemented rigorously. Using these coherent states, one arrives at a path integral representation of the partition function of the systems, from which the effective Hamiltonians can be read off. We apply this method to the t-J model on the square lattice and on the triangular lattice. In the former case, we reproduce the well-known fermion-boson Hamiltonian for a hole in a collinear antiferromagnet. We demonstrate that our method also works for non-collinear antiferromagnets by calculating the spectrum of a hole in the triangular antiferromagnet in the self-consistent Born approximation and by comparing it with numerically exact results.
PACS. 75.10.Jm Quantized spin models - 71.10.Fd Lattice fermion models - 75.50.Ee Antiferromagnetics
(a) email: koerner@itp.uni-hannover.de
Article in PDF format (638 KB)
Online publication: October 26, 1998
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