Structural and magnetic studies of Co and Fe implanted BaTiO3 crystals

Singly-charged Co or Fe ions with energy 40keV were implanted into single-domain ferroelectric plates of barium titanate (BaTiO3) with high fluences in the range of (0.5-1.5)1017ion/cm2 to create new magnetoelectric materials. Scanning electron microscopy (SEM) and conversion electron Mossbauer spectroscopy (CEMS) studies have shown that high-fluence implantation with 3d-ions results in formation of cobalt or iron nanoparticles in the near-surface irradiated region of perovskite-type crystal. With increasing the fluence, the both Co- and Fe-implanted BaTiO3 samples reveal at first superparamagnetic, and then ferromagnetic properties at room temperature. Analysis of magnetic hysteresis loops measured in the in-plane and out-of-plane geometries have shown that ferromagnetic BaTiO3:Co(Fe) nanocomposite layers display the "easy plane" magnetic anisotropy similar to that found for thin granular magnetic films. Together with our previous observation of the magnetoelectric effect in these samples, our structural and magnetic investigations show that the ion implantation is suitable to synthesize the desired magnetoelectric nanocomposite materials.