Investigating the Ferroelectric Potential Landscape of 3R-MoS$_2$ through Optical Measurements

Abstract: In recent years, sliding ferroelectricity has emerged as a topic of significant interest due to its possible application in non-volatile random access memory. This phenomenon is unique to two-dimensional van der Waals materials, where vertical ferroelectric polarization switching is induced by relative in-plane sliding of the constituent layers. The intrinsic stacking order influences the resulting polarization, creating distinct polarization regions separated by domain walls. These regions and the domain walls can be manipulated using an applied vertical electric field, enabling a switchable system that retains the environmental robustness of van der Waals materials under ambient conditions. This study investigates 3R-MoS$_2$ using various optical measurement techniques at room temperature. The spatially resolved optical measurements reveal apparent signal changes corresponding to different ferroelectric stacking orders and variations in layer count. Our findings demonstrate that fast optical mapping at room temperature is a reliable method for probing ferroelectric potential steps in 3R-stacked MoS$_2$ samples, thereby facilitating the identification of the ferroelectric configuration. This approach does not require a conductive substrate or an electrical contact to the sample, making it more versatile than traditional atomic force probe techniques.