Building a Magneto-optical Kerr Microscope and Characterizing Magnetic Nanocap Thin Films

The magneto-optical Kerr effect (MOKE) magnetometry method using a laser is an effective characterization tool capable of measuring local magnetic hysteresis loops of magnetic samples in sub-micron size. However, a laser system is not optimal for imaging magnetic domains. Therefore, we developed a homemade MOKE microscope by modifying a regular polarizing microscope and implemented an electromagnet to observe the switching of the magnetic domains. Permalloy (Py) and SmCo nanocaps were fabricated on nano/microsphere templates using a pioneering fabrication method of nanosphere lithography. By using the MOKE method on our samples, we observed contrasts that reflected the presence of magnetic domains of the micrometer scale. By measuring both hysteresis loops and magnetic domains we expect to provide an understanding of the magnetic characteristics of three-dimensional magnetic nanostructures such as our nanocap thin films.