Perovskite-type $\mathrm{EuTi}{\mathrm{O}}_3$, which is quantum paraelectric and $G$-type antiferromagnetic (AFM) in the bulk form, has attracted great attention due to its strong spin-lattice coupling and strain-induced multiferroic in thin film form. In this study, significant magnetodielectric (MD) coupling is demonstrated in ${\mathrm{K}}_2\mathrm{Ni}{\mathrm{F}}_4$-type ferromagnetic (FM) layered perovskite $\mathrm{E}{\mathrm{u}}_2\mathrm{Ti}{\mathrm{O}}_4$, which features alternating rocksalt (RS)-type EuO layers and perovskite (Pv)-type $\mathrm{EuTi}{\mathrm{O}}_3$ layers. We find a dielectric anomaly as a local minimum of permittivity near the ferromagnetic transition temperature ($T_{\mathrm{C}}=9.5\mathrm{K}$) in the temperature-dependent permittivity under zero magnetic field. Remarkably, an applied magnetic field induces a substantial increase in permittivity at $T_{\mathrm{C}}$ (approximately 22% at 3 T), which is three times larger than that observed in bulk $\mathrm{EuTi}{\mathrm{O}}_3$. Our experimental and first-principles studies reveal that the insertion of EuO layers in $\mathrm{E}{\mathrm{u}}_2\mathrm{Ti}{\mathrm{O}}_4$ enhances the Eu-$f$/Ti-$d$ orbitals hybridization through pseudostrain in the $\mathrm{EuTi}{\mathrm{O}}_3$ layers, as well as modifies the magnetic exchange paths that favor ferromagnetism over antiferromagnetism. The enhanced hybridization highlights the role in the large MD coupling played by AFM superexchange interactions via the Ti $3d$ state, which competes with indirect FM interactions via the Eu $5d$ state. Our findings demonstrate the potential of layered structure to control MD coupling, paving the way for new strategies in designing MD materials.

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• Magneto-dielectric effect
• Perovskites
• Rare-earth magnetic materials