Development of a SEMPA system for magnetic imaging with ns time resolution and phase-sensitive detection

Scanning electron microscopy with polarization analysis is a powerful lab-based magnetic imaging technique offering parallel imaging of multiple magnetization components and a very high spatial resolution. However, one drawback of the technique is the long required acquisition time resulting from the low inherent efficiency of spin detection, which has limited the applicability of the technique to certain quasi-static measurement schemes and materials with strong contrast. Here we demonstrate the ability to improve the signal-to-noise ratio for particular classes of measurement involving periodic excitation of the magnetic structure via the integration of a time-to-digital converter to the system and a digital lock-in detection scheme. The modified setup provides dynamic imaging capabilities using selected time windows and finally full time-resolved imaging with a demonstrated time resolution of better than 2 ns.