A platform for time-resolved scanning Kerr microscopy in the near-field.

摘要: Time-resolved scanning Kerr microscopy (TRSKM) is a powerful technique for the investigation of picosecond magnetization dynamics at sub-micron length scales by means magneto-optical effect (MOKE). The spatial resolution conventional (focused) using microscope objective lens determined optical diffraction limit so that nanoscale character lost. Here we present platform to overcome this limitation near-field TRSKM incorporates an atomic force (AFM) with access metallic AFM probe aperture its tip. We demonstrate capability instrument through comparison time-resolved polar images within microscale NiFe rectangle acquired both and focused techniques wavelength 800 nm. flux-closure domain state in-plane equilibrium provided maximum possible dynamic contrast across central wall enabled assessment each technique. Line profiles extracted from was enhanced respect images. Furthermore, signal (∼1 mdeg) more than half signal, despite potential loss light due internal reflections have confirmed operation exploring influence tip-sample separation be ∼550 nm sub-wavelength diameter 400 in good agreement finite element modeling aperture. Large amplitude electric field along regions modeled lie perpendicular incident polarization indicate can support plasmonic excitations. comparable signals suggest such excitations may lead MOKE. This work demonstrates performed without significant diminution relatively large, apertures, while development utilizing antennas specifically designed measurements deeper into discussed.