Spin-Wave Impurity Effects in Iron-Manganese Ferrites

Studies of the temperature dependence of the 55Mn nuclear magnetic resonance in the system MnxFe3−xO4 for 0.1≤x≤1 are presented. From the experimentally determined temperature dependence of the local magnetization, we obtain evidence for the importance of spin-wave impurity effects in the region of dilute Mn impurities in Fe3O4. A comparison of the data from Mn1Fe2.9O4 with Boyd's 57Fe NMR data for A sites in Fe3O4 shows that the magnetization at the impurity manganese sites is falling off more rapidly with temperature than the host Fe3O4 magnetization. This is consistent with an increased probability of finding a spin deviation at manganese sites as expected for JMn-Fe