Abstract
The spin-wave excitations and the critical behavior of the sublattice magnetization in Bi2CuO4 have been investigated by means of neutron scattering. The three-dimensional character of the antiferromagnetic ordering with propagation vector K=(1,0,0) below TN=45.83(8) K is reflected by the value of the critical exponent β=0.352(3). The spin-wave excitations have been measured along the symmetry directions [100] and [001]. The spin-wave dispersion is found to split into two branches with energy gaps Δ1=2.1 meV and Δ2=3.4 meV at the zone center. The data analysis is based on an S=1/2 spin Hamiltonian of tetragonal symmetry with anisotropic bilinear exchange including a four-site exchange interaction term.
Published Version
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