The Influence of KrF Excimer Laser Annealing on Magnetic and Structural Properties of FePt/PtIr Thin Films

A series of 60-nm FePt thin films were deposited by RF magnetron sputtering system on Si/SiO₂ substrate. Platinum–iridium alloy was deposited as a buffer film between the FePt thin film and Si/SiO₂ substrate. These films were annealed by KrF excimer laser annealing with 248 nm of wavelength. The number of laser pulses which were applied on the film was varied from 3 to 20. The A₁ to L₁₀ phase transformation of FePt was confirmed by X-ray diffraction. Three pulses of laser were not sufficient for A₁ to L₁₀ phase transformation. A maximum order parameter of 0.91 was obtained after applying 18 pulses of laser. The roughness of films changed in different pulses, and the films were in the best condition after applying 18 pulses; the roughness was 3.51 nm and its morphology that was observed from AFM was 129 nm. The maximum coercivity was 0.61 MA/m. The coercivity increased with the application of different pulses of laser. Increasing coercivity to the maximum value of 0.61 MA/m related to grain growth. Coercivity of samples in 3, 6, 9, 12, 18, and 20 pulses was 0.24, 0.402, 0.488, 0.522, 0.64, and 0.6 MA/m respectively. Determining the grain growth under condition of annealing was done by field emission scanning electron microscopy (FESEM). Growth of all specimens was calculated with imager software. Grain size in as deposited and 3, 6, 9, 12, and 18 pulses of laser was 15, 20, 29, 44, 47, and 59 respectively.