Dielectric and spin relaxation behaviour in DyFeO 3 nanocrystals

We report the temperature and frequency dependent dielectric measurements and ac magnetic susceptibility of chemically synthesized DyFeO 3 nanoparticles (size ∼50-60nm). The measurement of the dielectric properties was carried out in a broad temperature (20-325K) and frequency (1-10 6 Hz) range. The non-Debye type dipolar relaxation phenomenon was observed in the DyFeO 3 nanoparticles, as confirmed by the Cole-Cole plots. The higher values of ɛ′ at the lower frequencies are explained on the basis of the Maxwell-Wagner model. The Cole-Cole analysis enabled us to separate the contribution of relaxation times, resistance and capacitance in grain and grain boundaries in DyFeO 3 nanocrystals. We found that with increasing temperature, the contribution of grain boundary resistance increases in comparison to the grain resistance. We also performed spin relaxation studies in a broad temperature and frequency range. Both the in-phase (χ′) and out-of-phase (χ″) components of the ac magnetic susceptibilities of the DyFeO 3 nanoparticles show a clear evidence at spin reorientation transition around 70K and T N (Dy) around 4K as reported by us in our earlier study using the dc magnetic behaviour.