Magnetism in Mn-doped ZnO bulk samples

Magnetic properties of Mn-doped ZnO (Zn0.98Mn0.02O) bulk materials prepared by the solid state reaction method were investigated by measuring magnetization as functions of temperature and magnetic field. The results indicate that the samples sintered in Ar gas show ferromagnetic behavior at room temperatures, but it disappears in samples sintered in air. Even for ferromagnetic samples, the obtained saturation value of magnetization is much smaller than theoretical value, suggesting the possibility of that there was a strong anti-ferromagnetic exchange coupling in this kind of compounds.