Comment on "Colossal dielectric and magnetodielectric effect in Er(2)O(3) nanoparticles embedded in a SiO(2) glass matrix"

In a recent paper, Mukherjee et al. [Phys. Rev. B 82, 104107 (2010)] reported a colossal enhancement of dielectric constant along with magnetodielectric (MD) behavior in a SiO2-Er2O3 system synthesized via the sol-gel route. In the opinion of the authors of the criticized paper, such a colossal MD effect in the measured samples is a direct consequence of exploiting magnetoresistance changes associated with the size and concentration of Er2O3 nanoparticles. We point out that the disappearing MD behavior depends on the crystallite size and dopant concentration, as shown by the authors of the criticized paper, but also on the nature and the crystal structure of the compound.