Study of magnetic dynamics of LuFe₂O₄

A detailed study of the magnetic properties has been carried out for the LuFe₂O₄ system. Room temperature X-ray diffraction indicated single phase of the polycrystalline powder. The dc magnetization reveals the magnetic transition near 225 K. The ac susceptibility showed a peak corresponding to the magnetic transition; however, the peak is found to be frequency-dependent. With increasing frequency, the peak-temperature of the real part of the ac susceptibility (X′) increases and the respective susceptibility values are decreased. The imaginary part of the ac susceptibility (X″) increases with increasing frequency and so as the magnetic peak-temperature. The dynamic scaling of the ac susceptibility reveals the spin glass nature of this phase. The unusual glassy nature of the magnetic transition seems to be related to the presence of fractional disorder of the Fe ²+ and Fe³+ ions resulted from the oxygen nonstoichiometry.