A. Celic et al., NEW APPROACH TO SURFACE MAGNON STATES IN THE SEMIINFINITE ANTIFERROMAGNETIC HEISENBERG-MODEL WITH BIQUADRATIC EXCHANGE AND SINGLE-ION-ANISOTROPY, Physics letters. A, 219(1-2), 1996, pp. 121-130
We present a new approach to the study of excitations in a semi-infini
te antiferromagnet described by the Heisenberg Hamiltonian with biquad
ratic exchange and single-ion anisotropy.