Pressure-induced isostructural electronic topological transitions in 2H-MoTe₂: x-ray diffraction and first-principles...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Molybdenum ditelluride (MoTe2) exhibits diverse polytypes with unique electronic and structural properties.
• Understanding pressure-induced phase transitions is crucial for novel material applications.

Purpose of the Study:

• To investigate the high-pressure behavior of 2H-MoTe2 using experimental and theoretical methods.
• To identify and characterize pressure-induced structural and electronic topological transitions.

Main Methods:

• Synchrotron x-ray diffraction measurements on powder 2H-MoTe2 up to ~46 GPa.
• First-principles based density functional theoretical analysis.
• Analysis of lattice parameters, compressibility, and bulk modulus.

Main Results:

• An isostructural transition was observed around 7 GPa, linked to anomalies in the c/a lattice parameter ratio and layer compressibility.
• Two electronic topological transitions (Lifshitz-type) were identified at higher pressures.
• A significant change in bulk modulus occurred at the first electronic topological transition (~20 GPa).
• A minimum in the c/a ratio around 32 GPa indicated the second electronic topological transition.

Conclusions:

• 2H-MoTe2 undergoes an isostructural transition and two electronic topological transitions under quasi-hydrostatic pressure up to 46 GPa.
• These transitions are associated with significant changes in electronic band structure and material compressibility.
• No overall structural phase transition was observed within the studied pressure range.