Structural stabilities, electronic structures, and superconductivity properties of GexS1−x compounds under high pressure

Abstract

Controversial results exist between the available experimental data and density functional theory calculations for germanium sulfide structures under high pressure conditions. In the realm of semiconductive materials, novel phases derived from Ge_xS_1−x compounds present a significant opportunity for advancements in electronic applications. In this study, we conducted an in-depth analysis of the thermodynamic stability, electronic features, and superconducting characteristics of germanium sulfide compounds under various pressures employing DFT calculations. Our exploration covers phase transitions, modifications in the band structure, and the emergence of superconductivity within the Ge_xS_1−x family, with a particular emphasis on GeS, GeS₂ and GeS₄. The research reveals that these compounds experience marked phase transitions when subjected to pressure, which leads to metallization and alterations in the electronic structure, potentially facilitating transitions from semiconductor to metal states. Notably, the metallization process of the Pnma-2 phase of GeS exhibits an intriguing band structure variation driven by germanium and sulfur atoms within the pressure range of 6–19 GPa. In addition, the Pmm phase of GeS demonstrates superconductivity. Simulated by two different methods, the critical temperatures are identified as 7.8 K and 28.3 K at 60 GPa as well as 2.7 K and 16 K at 120 GPa. The potential reasons for the differences and changes in T_c and in the strength of the electron–phonon coupling due to pressure have been examined. This investigation sheds light on the complex interactions between structural transitions, adjustments in electronic band structure, and superconductivity, highlighting the pivotal role of pressure in these processes. The findings not only broaden our comprehension of the intricate phase behavior and electronic properties of Ge_xS_1−x compounds but also underscore the prospects for the synthesis of novel phases with distinctive attributes. This research paves the way for future studies on the practical application of these materials in the realm of electronic and superconducting devices, thereby making significant contributions to the fields of materials science and condensed matter physics.