Journal Article

On the Optical Properties of Crsub.2Gesub.2Tesub.6 and Its Heterostructure

Tanigaki, Katsumi, Pan, Xing-Chen, Chen, Yong P, Matsuda, Takuya, Llacsahuanga Allcca, Andres E, Haglund, Amanda Victo, Idzuchi, Hiroshi, Mandrus, David

2023

Overview

Recently, there has been a growing interest in two-dimensional van der Waals (vdW) magnets owing to their unique two-dimensional magnetic phenomena and potential applications. Most vdW ferromagnets have the Curie temperature below room temperature, highlighting the need to explore how to enhance their magnetism. In our previous report, we successfully increased the Curie temperature of the prototypical vdW magnet Cr[sub.2]Ge[sub.2]Te[sub.6] using a NiO overlayer. In layered materials, the presence of wrinkles is often observed and evaluating them using optical microscopy proves to be useful; however, there have been limited investigations into the optical constants of vdW magnets, hampering progress in understanding their optical properties. In this study, we present the optical constants of Cr[sub.2]Ge[sub.2]Te[sub.6] obtained through ellipsometry measurements. To account for the presence of wrinkles, we model a vacuum region between the substrate and the vdW magnet, and we calculate the reflectivity as a function of wavelength and vacuum thickness to visualize the optical image. Furthermore, we discuss the relationship between the optical constants and the electronic structure of the material.

• Publisher: MDPI AG
• Subject: Ferromagnetism / Optical properties