Nd-Fe-B Thin Films with Perpendicular Magnetic Anisotropy and High Coercivity Prepared by Pulsed Laser Annealing

Amorphous, as-deposited Nd-Fe-B films prepared by RF-sputtering were annealed by irradiating pulsed KrF excimer laser (248 nm). A pulse of 20 ns in width and 4 kJ/m² in power density was irradiated onto a 2 μm-thick as-deposited film kept at 400°C. It is observed that, by a single shot of the pulse, Nd₂Fe₁₄B φ phase crystallized with prominent texturing of c-axis along the film normal. Annealed films showed excellent magnetic characteristics; M_s= 0.978 T, M _r = 0.906 T, _iH_c = 1272 kA/m, and (BH) _MAX = 161 kJ/m³. This process is also found to be successfully applicable to a 20 μm-thick film. Using 2 μm-thick as-deposited film kept at 400°C, micro-magnet patterns of 100 μumin width and 1-2 mm in length were fabricated by irradiating a 20-ns pulse shot through a patterned mask. The patterned area revealed that magnetizations are directed along the film normal with coercivity higher than 1200 kA/m.