Frequency dependent magneto-dielectric effect in bilayer manganite Pr(Sr$_{0.1}$Ca$_{0.9})_{2}$Mn$_{2}$O$_{7}$*

We report novel frequency dependent magneto-dielectric effect and a strong dielectric anomaly near Neel temperature (T$_{N})$ in a single crystal of bilayer manganite Pr(Sr$_{0.1}$Ca$_{0.9})_{2}$Mn$_{2}$O$_{7}$ system. The magneto-dielectric effect measured in a field of 3T shows large frequency dependence and reaches a maximum ($\sim $25{\%}) near T$_{N}$ at a measurement frequency of 1 kHz. Change in frequency leads to a change in the sign of the effect. There is a sizeable dielectric relaxation process near T$_{N}$, which exhibits an activated behavior and strongly non-Debye nature at or below T$_{N}$ while becoming Debye like at higher temperature.