Origin of spin-glass behavior of Zn₁-xMn_xO

ac susceptibility has been studied for polycrystalline Zn$_{1-x}$Mn$_x$O. Stoichiometric samples demonstrate Curie-Weiss behavior, which indicates mostly antiferromagnetic interactions. Magnetic susceptibility can be described by a diluted Heisenberg magnet model developed for semimagnetic semiconductors. High-pressure oxygen annealing induces spin-glass like behavior in Zn$_{1-x}$Mn$_x$O by precipitation of ZnMnO$_3$ in the paramagnetic matrix.