Nanoscale spin and topological optical texture in advanced magneto-optic microscopy

Abstract

Magneto-optic Kerr effect microscopy is an irreplaceable technique in spintronics, offering high-speed imaging on surface magnetization. Nevertheless, as the research of interest in spintronics is miniaturized and complicated due to the topological physical phenomena, optical metrology encounters limitations. Overcoming the low visibility and optical diffraction limit can pave a way for applications toward ultrafast spintronics study and real-time imaging on topological textures. In this study, I suggest three types of advanced magneto-optic microscopy to observe nanoscale spin textures and topological optical textures. First, I propose extreme anti-reflection enhanced magneto-optic Kerr effect microscopy to observe nanoscale magnetic domain reversal. A significant enhancement of visibility and magnetic circular birefringence was achieved based on the extremely high polarization rotation angle of 20 degrees. Furthermore, observation of nanoscale Barkhausen jumps and their statistical analysis was conducted by real-time confocal measurement. Second, I observed nanoscale magnetic domain walls and skyrmions based on dark-field magneto-optic Kerr effect microscopy. The Purcell effect from the reflective substrates resonantly enhanced the magneto-optic scattering from the magnetic domain wall. Based on the result, imaging of subwavelength scale skyrmions was achieved. Finally, I observed the topological and dynamic properties of magnetically active optical vortices under magneto-optic off-axis holography. I demonstrated the spontaneous generation of optical vortices in the gradient-thickness optical cavity. Holographic images under the magnetic field analyze the dynamic behaviors of the spontaneously generated optical vortices.