Real-time monitoring of order-disorder transformation of FePt thin films by light scattering

An optical method is proposed to real-time monitor the order transformation of FePt thin films. By measuring the surface reflection amplitude, onset temperature can be determined correctly. In a heating process, order transformation drastically increases the surface roughness due to recrystallization and grain growth, resulting in rapid drop of surface reflectivity. By tracking this drop, the kinetic ordering temperature can be determined. Experimentally measured kinetic ordering temperature for Fe50.4Pt49.6, Fe46.6Pt53.4, and Fe52.7Pt47.3 thin films of 60 nm in thickness are 396 degrees C, 437 degrees C, and 368 degrees C, respectively. They are in good agreement with the published DSC data.

Automated summary

An optical method has been proposed to monitor the order transformation of FePt thin films in real-time, with the onset temperature determined accurately by measuring surface reflection amplitude. The experimentally measured kinetic ordering temperatures for different compositions of FePt thin films are in good agreement with published DSC data, confirming the effectiveness of the optical method in tracking order transformation.