A novel colossal magnetodielectric effect in Er$_{2}$O$_{3}$ nanoparticle embedded SiO$_{2}$ glass matrix around room temperature

An intriguing colossal magnetodielectric (MD) behavior is observed in nanocrystalline Er$_{2}$O$_{3}$ (0.5 mol{\%}) embedded SiO$_{2}$ glass matrix synthesized via sol-gel route. At around 9 T magnetic field, the dielectric constant of this superparamagnetic Er$_{2}$O$_{3}$ nanoparicle ($\sim $5 nm) composite reached almost \textit{$\sim $}2.75 times the corresponding value of pure Er$_{2}$O$_{3}$. The MD effect arising due to the strong coupling between the magnetic moment and the lattice strain depends on the nanoparticle size and separation, which can be controlled by proper annealing. This novel MD system might be treated as a potential candidate for device miniaturization.