Nanoimprint lithographic surface patterning of sol-gel fabricated nickel ferrite (NiFe₂O₄)

Textured nickel ferrite (NFO, NiFe2O4) thin films were deposited at room temperature by chemical solution deposition onto c-plane sapphire substrates. A nanoimprint lithography technique using a polydimethylsiloxane stamp was used to transfer a pattern from a master to the thin film, which was subsequently annealed to crystallize the NFO. Atomic force microscopy scans showed good periodicity and feature profile over a large area which was confirmed with cross-sectional transmission electron microscopy. X-ray diffraction revealed textured single-phase inverse spinel NFO. Magnetic measurements of patterned thin films showed a large reduction in coercivity due to demagnetization factors.