Further development of a scanned near-field optical microscope for magneto-optic Kerr imaging of magnetic domains with 10nm resolution

Publisher Website
Google Scholar
Abstract
Work is described on the development of a scanning near-field optical microscope (SNOM) for the primary purpose of imaging magnetic systems with resolution on the order of 10 nm. Since many magnetic materials are optically opaque, it is desired to have a probe which is appropriate for reflection mode. In addition, the near-field probe must be linearly polarizable, since the magneto-optic Kerr effect (MOKE) will provide the contrast mechanism necessary for magnetic imaging. Data is presented on the characterization and use of approximately 30 nm diameter Ag particles as probes for MOKE-sensitive SNOM. Such small metal particles exhibit a localized plasmon resonance in the visible, which greatly enhances their optical scattering cross-section. Ag particles prepared by colloidal chemistry techniques have been deposited on bismuth doped YIG and silica-coated Permalloy to measure the magnitude of the near-field MOKE. The optical apparatus used to measure near-field MOKE is described. Hysteresis loop data is presented for Bi-YIG using the near-field MOKE. The effect is also seen in Permalloy, with a surprisingly large peak-to-peak rotation of 3 milliradians. A heuristic model is proposed for explaining the near-field MOKE in longitudinally magnetized materials. Finally, it is reported that we now have conventional MOKE microscopic imaging capabilities which will allow us to observe magnetic domain structures in weak magneto-optic materials, such as Permalloy.

This publication has 0 references indexed in Scilit: