Magneto-Optical Properties of Homogeneous and Graded Co-Pt Thin Films

There is renewed interest in investigating properties of magnetic thin films with a graded composition that can host room temperature magnetic skyrmions [1,2,3]. A graded composition leads to a varying Dzyaloshinskii-Moriya interaction (DMI), considered essential to observe the desired properties. In this work, we will present the magneto-optical properties of CoPt films to investigate the effect of thickness (10-50 nm) and composition (homogeneous vs gradient) using the magneto-optical Kerr effect (MOKE). The properties of graded CoPt films will be compared to homogeneous films, and direct imaging of the magnetic domains will be performed using magnetic force microscopy (MFM). X-Ray diffraction (XRD) measurements of the crystal structure reveal a strong CoPt peak in both homogeneous and graded samples. Preliminary MOKE studies suggest adding a buffer layer of Pt decreases the coercivity of the hysteresis loops while maintaining the MOKE signal. The next steps are to examine the samples using MFM and polar MOKE. By correlating the structure and magneto-optical properties, we hope to improve the understanding of the properties that promote skyrmions.

[1] https://doi.org/10.1021/acsnano.4c10145     

[2] https://doi.org/10.1002/smll.202505204

[3] DOI: 10.1021/acs.nanolett.2c03973