Pressure-dependent Semiconductor to Semimetal and Lifshitz transitions in 2H-MoTe${}_2$: Raman and First-principles studies

Abstract

High pressure Raman spectroscopy of bulk 2H-MoTe${}_2$ upto $\sim$ 29 GPa is shown to reveal two phase transitions (at $\sim$ 6 and 16.5 GPa), which are analyzed using first-principles density functional theoretical calculations. The transition at 6 GPa is marked by changes in the pressure coefficients of A${}_{1g}$ and E${}_{2g}^1$ Raman mode frequencies as well as in their relative intensity. Our calculations show that this is an isostructural semiconductor to a semimetal transition. The transition at $\sim$ 16.5 GPa is identified with the changes in linewidths of the Raman modes as well as in the pressure coefficients of their frequencies. Our theoretical analysis clearly shows that the structure remains the same upto 30 GPa. However, the topology of the Fermi-surface evolves as a function of pressure, and abrupt appearance of electron and hole pockets at P $\sim$ 20 GPa marks a Lifshitz transition.

20 Pages, 8 Figures

References in corpus (7)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides
• Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides
• Pressure induced metallization with absence of structural transition in layered MoSe2
• Double resonance Raman modes in mono- and few-layer MoTe${}_2$
• Sharp Raman Anomalies and Broken Adiabaticity at a Pressure Induced Transition from Band to Topological Insulator in Sb2Se3
• Doped graphene as tunable electron-phonon coupling material