Ferris-Wheel Magneto-Optic Kerr Effect and Optical Hall Effect Technique

It is well known that the anomalous Hall effect displayed in ferromagnets is much stronger than the ordinary Hall effect. Similarly, the magneto-optical Kerr effect (MOKE) is orders of magnitude stronger than the optical Hall effect taking place in normal metals. Here, we present a MOKE technique that we term the “Ferris” MOKE which is based on large-amplitude modulation of the externally applied magnetic field such that the sensitivity is enhanced by more than an order of magnitude. Consequently, the Ferris MOKE is found suitable for measurement of the optical Hall effect at visible light wavelengths where the effective electrical displacement is short. We derive a model that builds on the Lorentz-Drude formalism that accounts for the evanescent waves in the metal. By complementing the measurements with carrier density data extracted by DC Hall measurements, we show that the “Ferris MOKE” measurement can reproduce previously reported effective masses that is indicative of the effective band curvature. Since the optical cycle is much shorter than the Drude mean free path, the technique may prove useful for probing intrinsic properties of the band structure and topological states of matter in non-magnetic materials.