Néel transition and sublattice magnetization of pure and dopedLa2CuO4

Abstract

We have measured the sublattice magnetization of stoichiometric ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ (${\mathit{T}}_{\mathit{N}}$=325 K) and ${\mathrm{La}}_2$ ${\mathrm{Cu}}_{0.95}$ ${\mathrm{Zn}}_{0.05}$ ${\mathrm{O}}_4$ (${\mathit{T}}_{\mathit{N}}$=157 K). We discuss the data for ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ and other lamellar copper oxides in terms of the quantum Heisenberg model including weak XY anisotropy and interlayer coupling. Spin-wave theory and a generalized Schwinger-boson mean-field theory are used to predict the ordered moment as a function of temperature without adjustable parameters. We also discuss the influence of different dopants on the Néel temperature and sublattice magnetization.