Influence of Fe substitution on multiferrocity and magneto-dielectric properties in CoCr2O4

The present work reports the magnetic, dielectric, ferroelectric, magneto-dielectric and magneto-electric coupling/behavior of two polycrystalline compounds of Fe substituted CoCr2O4, i.e. Co(Cr0.95Fe0.05)(2)O-4 and Co(Cr0.925Fe0.075)(2)O-4. Dielectric anomalies observed at the onset of the collinear ferrimagnetic (FIM) transition (T-C), compensation temperature (T-comp), non-collinear magnetic spin-spiral transition (T-S) and lock-in transition (T-L), which depict the magnetodielectric coupling in the studied compounds. The ferroelectric transition has been observed around 24 and 23 K for Co(Cr0.95Fe0.05)(2)O-4 and Co(Cr0.925Fe0.075)(2)O-4, respectively. Significant change in magnitude of ferroelectric polarization by the application of magnetic field reveals the magnetoelectric (ME) coupling in the studied compounds. The novel result of this work is that the nature of magnetodielectric coupling changes across the compensation temperature in the collinear FIM region. Based on the Landau theory, we deduce that the magnetodielectric coupling across T-comp appears to originate from (PM2)-M-2 term in the total free energy. Our results also suggest that the strength of the polarization scales with the application of the external magnetic field.