Synthesis of iridescent Ni-containing anodic aluminum oxide films by anodization in oxalic acid

• Iridescent Ni-containing anodic aluminum oxide films were successfully fabricated.
• Precisely controllable color tuning could be obtained using wet-chemical etching.
• Magnetization reversal mechanism is in good agreement with symmetric fanning model.
• Such colored films could be used in multifunctional anti-counterfeiting applications.

Ni-containing anodic aluminum oxide films with highly saturated colors were synthesized using an ac electrodeposition method, and the optical and magnetic characteristics of the films were characterized. Precisely controllable color tuning could be obtained using wet-chemical etching to thin and widen the anodic aluminum oxide films pores isotropically before Ni deposition. Magnetic measurements indicate that such colored composite films not exhibit obvious easy magnetization direction. The resulted short (200 nm in length) and wide (50 nm in diameter) Ni nanowires present only fcc phase. The magnetization reversal mechanism is in good agreement with the symmetric fanning reversal mode which is discussed in detail. Such films may find applications in decoration, display and multifunctional anti-counterfeiting applications.

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