Microstructure and magnetic properties of FePt thin films for the coating of magnetic force microscopy tips

L1₀-FePt thin films with (111)-texture were deposited on Si(100) substrates at various atomic ratios and annealing temperatures to be used as a cover layer for magnetic force microscope (MFM) tips. Their microstructure and magnetic properties were systematically studied. The experimental results indicate that both atomic ratio and annealing temperature affect the disorder-order transformation of FePt films. In particular, when the atomic ratio approaches 1:1 (Fe: 51 at.%, Pt: 49 at.%) and the annealing temperature is 600 °C, the FePt film exhibits an ultra-high in-plane coercivity of 13.2 kOe. This is attributed to the formation of an L1₀-FePt phase with high order parameters. Based on the optimal preparation parameters, MFM tips were prepared by depositing FePt films on non-magnetic Si tips. Magnetic domain structures of magnetic tape and magnetic recording medium were successfully observed using these home-made FePt MFM tips. Therefore, the high coercivity L1₀-FePt films with (111)-texture prepared on Si substrates are expected to be potential materials for the fabrication of MFM tips.