First-principles calculations of electronic, optical and thermodynamic properties of MTe (M=Ge, Sn): Spin-induced modulations in electronic and optical properties

To unlock the potential of two-dimensional (2D) transition metal chalcogenides (TMCs), it is essential to achieve precise engineering of their properties to meet the application demands. By manipulating key parameters such as thickness, composition and spin, the inherent properties of TMCs can be tailored to align with targeted functionalities. In this study, we have used First-principles DFT calculations to determine the structural, electronic, and optical properties of GeTe (rhombohedral) and SnTe (cubic) with and without spin polarization effect. The electronic structure calculations of MTe (M=Ge, Sn) prove that the inclusion of spin-orbit coupling (SOC) modifies the band structure, specifically near the Fermi level. The calculated optical properties without SOC shows prominent peaks in infrared spectral regions. However, after applying SOC, the peaks are reduced due to band structure modification and re-distribution of optical transitions. The thermodynamic properties of these two materials were investigated. Both materials demonstrate remarkable thermal stability, with heat capacity increasing at lower temperatures and approaching the Dulong-Petit limit at higher temperatures. Of note, these results elucidate the role of SOC in modulating structural and optical properties. Further, our findings offer valuable insights into the thermodynamic parameters of MTe.