Effect of A-site substitution on the magnetic and dielectric behaviors of YMnO3 based ferroelectric thin films

Dielectric and magnetic properties of A-site substituted YMnO₃ ceramics and epitaxial films were studied. Stoichiometric polycrystalline bulk sample exhibit p-type conduction due to the existence of Mn⁴⁺. The I-V property is well explained the Pool-Frenkel type carrier emission, and the activation energy is calculated to be 0.38 eV. The carrier density decreases by Zr doping and increases by Li or Mg doping. Although all the samples exhibit antiferromagnetic magnetization behavior against the applied magnetic field at 5 K, carrier doped samples displays parasitic ferromagnetic behavior (weak ferromagnetism). Epitaxial films show distinct ferroelectric property and also exhibit antiferromagnetism. Substituting Y with Yb enhances the ferromagnetic interaction.