Tunable Three-Phase Co–CeO₂–BaTiO₃ Hybrid Metamaterials with Nano-Mushroom-Like Structure for Tailorable Multifunctionalities

Recent studies in complex nanocomposite thin films have brought forth interesting morphologies and physical properties and thus great potential for future devices. This study presents the formation of a nanomushroom structure developed from a complex three-phase nanocomposite system, i.e., the Co–CeO2–BaTiO3 (Co–CeO2–BTO) system. Via varying the oxygen partial pressure during deposition, the Co–CeO2–BTO system growth shows a microstructure tuning of vertically aligned Co nanopillars in a CeO2–BTO composite matrix processed in vacuum to the Co nano-mushroom-like structures under 200 mTorr oxygen. Such morphology tuning results in interesting physical property tuning such as magnetic anisotropy, optical anisotropy, and dielectric function tuning. This study suggests the effectiveness of morphology tuning via complex three-phase nanocomposite designs and processing condition variation. The resultant three-phase nanocomposite structures present great potential to address the needs on multifunctional hybrid materials for nanoscale optical and magnetic device demonstrations.