title: Long-range order and low-energy spectrum of diluted 2D quantum antiferromagnet.
abstract: The problem of a diluted two-dimensional quantum antiferromagnet on a square lattice is studied using spin-wave theory. The influence of impurities on static and dynamic properties is investigated and a good agreement with experiments and Monte Carlo data is found. The hydrodynamic description of spin waves breaks down at characteristic wavelengths Lambda greater than exp(const/x), x being an impurity concentration, while the order parameter is free from anomalies. We argue that this dichotomy originates from strong scattering of the low-energy excitations in two dimensions.
authors.affiliation: Department of Physics, University of California, Riverside, California 92521, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Chernyshev
authors.forename: Y C
authors.initials: YC
authors.lastname: Chen
authors.forename: A H
authors.initials: AH
authors.lastname: Castro Neto