High-Sensitivity Characterization of Ultra-Thin Atomic Layers using Spin-Hall Effect of Light

TL;DR

This paper introduces a novel, highly sensitive optical technique based on the spin-Hall effect of light for characterizing ultra-thin magnetic and dielectric layers, offering a practical alternative to traditional methods.

Contribution

It develops and demonstrates SHEL-MOKE as a versatile, non-invasive surface characterization tool with theoretical modeling and experimental validation for ultra-thin films and heterostructures.

Findings

SHEL-MOKE provides competitive sensitivity to standard MOKE.

The method successfully measures magnetic properties of ultra-thin films.

Theoretical models enable extraction of optical properties of non-magnetic layers.

Abstract

Magnetic/non-magnetic/heterostructured ultra-thin films' characterisation is highly demanding due to the emerging diverse applications of such films. Diverse measurements are usually performed on such systems to infer their electrical, optical and magnetic properties. We demonstrate that MOKE-based spin-Hall effect of light (SHEL) is a versatile surface characterization tool for studying materials' magnetic and dielectric ordering. Using this technique, we measure magnetic field dependent complex Kerr angle and the coercivity in ultra-thin films of permalloy (Py) and at molybdenum disulphide (MoS$_2$) - permalloy (MSPy) hetero-structure interfaces. The measurements are compared with standard magneto-optic Kerr effect (MOKE) studies to demonstrate that SHEL-MOKE is a practical alternative to the conventional MOKE method, with competitive sensitivity. A comprehensive theoretical model and simulation data are provided to further strengthen the potential of this simple non-invasive optical method. The theoretical model is applied to extract the optical conductivity and susceptibility of non-magnetic ultra-thin layers such as MoS$_2$ .