Magnetic dynamics inLa2CuO4with interlayer coupling and anisotropy gaps

Abstract

The role of anisotropy gaps in ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4--}$the in-plane gap of \ensuremath{\sim}10 meV, mainly due to the Dzyaloshinsky-Moriya antisymmetric exchange interaction, and out-of-plane anisotropy gap of \ensuremath{\sim}20 meV--together with interlayer coupling, is analyzed in the magnetic dynamics due to thermal excitation of spin waves, as revealed in temperature dependence of sublattice magnetization. By fitting with sublattice magnetization data for ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$, obtained from a M\"ossbauer-spectroscopic study, and incorporating the quantum correction ${\mathit{Z}}_{\mathit{c}}$ to spin-wave energy, we obtain the average planar exchange energy, ${\mathit{J}}_{\mathit{p}}$=1380 K, the ratio of effective interplanar-to-planar exchange energy, ${\mathit{r}}^{2}$=4.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$, and the characteristic energy for spin waves propagating perpendicular to the plane, 2${\mathit{Z}}_{\mathit{c}}$${\mathit{J}}_{\mathit{p}}$r=21 K.