Local magnetic impurities in the two-dimensional quantum Heisenberg antiferromagnet
Valeri N. Kotov, J. Oitmaa, Oleg P. Sushkov
The two-dimensional quantum Heisenberg antiferromagnet at zero temperature, with locally frustrating magnetic defects, is studied. We consider two types of defects---an isolated ferromagnetic bond (FMB) and a quantum impurity spin, coupled symmetrically to the two sublattices. A technique is developed to study strong defect-environment interaction. In the case of a FMB we find that, contrary to the previous linear spin-wave result, the local magnetization stays finite even for strong frustration. For an antiferromagnetic coupling of a quantum impurity spin with its environment, we find a local change in the ground state. All our calculations are compared with numerical results from exact diagonalization.
arXiv:cond-mat/9712281•Physical review. B, Condensed matter•Oct 1, 1998•14 citations