Numerical studies on the Heisenberg Antiferromagnet on a Square Lattice

Specialeforsvar ved Torsten Tranum Rømer


The quantum mechanical Heisenberg antiferromagnet on the square lattice has beeen investigated by exact diagonalization studies. The results are compared to both numerical and experimental results from the literature with special attention to neutron scattering data for CFTD obtained by Christensen et al. The analysis concentrates on an experimentally observed anomaly in both energy and intensity at the point (pi,0) in the two-dimensional Brillouin zone. The results of exact diagonalization were found to model the neutron scattering data and further suggested a possible explanation of the experimentally observed intensity anomaly.