Engineering the Structural and Electronic Phases of MoTe₂ through W Substitution

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Molybdenum Ditelluride (MoTe2) exists in multiple crystalline phases (2H, 1T', γ) with distinct electronic properties.
• The semiconducting 2H-phase is suitable for optoelectronics, while the semimetallic γ-phase exhibits topological properties.
• Phase transformations in MoTe2 can be induced by external stimuli, offering potential for novel functionalities.

Purpose of the Study:

• To investigate the effect of Tungsten (W) substitution on the phase stability of MoTe2.
• To map the phase diagram of the Mo1-xWxTe2 solid solution.
• To identify conditions for stabilizing the topological γ-phase of MoTe2.

Main Methods:

• Synthesis of Mo1-xWxTe2 solid solutions with varying W concentrations (x).
• X-ray diffraction and photoemission spectroscopy to characterize crystal structure and electronic properties.
• Analysis of the phase diagram to determine phase transition boundaries.

Main Results:

• A phase diagram for Mo1-xWxTe2 was established, showing a transition from semiconducting to semimetallic behavior with increasing W content.
• A critical W concentration (xc ≈ 8%) was identified, stabilizing the γ-phase at room temperature.
• The γ-phase was found to possess a Fermi surface similar to that of WTe2.

Conclusions:

• W substitution is an effective method to engineer the phase of MoTe2.
• The critical W concentration provides a pathway to stabilize the topological γ-phase, crucial for exploring its unique transport properties.
• Materials near the phase transition are promising candidates for electric-field-induced phase transformations, enabling advanced electronic devices.