Self-assembled vertically aligned Ni nanopillars in CeO₂ with anisotropic magnetic and transport properties for energy applications

Self-assembled vertically aligned metal-oxide (Ni-CeO₂) nanocomposite thin films with novel multifunctionalities have been successfully deposited by a one-step growth method. The novel nanocomposite structures presents high-density Ni-nanopillars vertically aligned in a CeO₂ matrix. Strong and anisotropic magnetic properties have been demonstrated, with a saturation magnetization (M_s) of ∼175 emu cm⁻³ and ∼135 emu cm⁻³ for out-of-plane and in-plane directions, respectively. Such unique vertically aligned ferromagnetic Ni nanopillars in the CeO₂ matrix have been successfully incorporated in high temperature superconductor YBa₂Cu₃O₇ (YBCO) coated conductors as effective magnetic flux pinning centers. The highly anisotropic nanostructures with high density vertical interfaces between the Ni nanopillars and CeO₂ matrix also promote the mixed electrical and ionic conductivities out-of-plane and thus demonstrate great potential as nanocomposite anode materials for solid oxide fuel cells and other potential applications requiring anisotropic ionic transport properties.