High-sensitivity characterization of ultra-thin atomic layers using spin-Hall effect of light

The fast-emerging diverse applications using a variety of magnetic/non-magnetic heterostructure ultra-thin films warrant the sensitive characterization of the electrical, optical, and magnetic properties of the interface. As a practical alternate to the conventional magneto-optic Kerr effect (MOKE) method, we propose and demonstrate the spin-Hall effect of the light (SHEL)-based MOKE method with competitive sensitivity and scope for further improvement. The SHEL-MOKE technique is a versatile surface characterization tool for studying materials’ magnetic and dielectric ordering, which are extracted from the variations to the phase-polarization characteristics of a focused beam of light reflected at the interface, as a function of the applied magnetic field. Using this technique, we measure the magnetic field dependent complex Kerr angle and the coercivity in ultra-thin films of permalloy (Py) and at molybdenum disulfide (MoS2)—permalloy (MSPy) hetero-structure interfaces. A comprehensive theoretical model and simulation data are provided to strengthen the potential of this simple non-invasive optical method. The theoretical model is subsequently applied to extract the optical conductivity of non-magnetic ultra-thin layers of MoS2.