Electroplated L10 CoPt thick-film permanent magnets

The fabrication and magnetic characterization of 15-μm-thick electroplated L10 CoPt hard magnets with good magnetic properties is reported in this paper. Experimental study of the dependence of the magnets' properties on annealing temperature reveals that an intrinsic coercivity Hci = ∼800 kA/m (10 kOe), squareness >0.8, and energy product of >150 kJ/m3 are obtained for photolithographically patterned structures (250 μm × 2 mm stripes; 15 μm thickness) electroplated on silicon substrates and annealed in hydrogen forming gas at 700 °C. Scanning electron microscopy is used to inspect the morphology of both the as-deposited and annealed magnetic layers, and X-ray Diffractometer analysis on the magnets annealed at 700 °C confirm a phase transformation to an ordered L10 CoPt structure, with a minor phase of hcp Co. These thick films are intended for microsystems/MEMS applications.