Intrinsic 1 phase induced in atomically thin 2H-MoTe₂ by a single terahertz pulse.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• The 2H to 1T’ polymorphic transition in molybdenum ditelluride (MoTe2) is technologically relevant for nanoscale transistors due to improved electrical performance.
• Previous studies suggested high-energy photon irradiation induced this transition, but results were controversial, with optical signatures attributed to tellurium clusters.
• A definitive method to induce and confirm the crystalline 1T’ phase of MoTe2 has been lacking.

Purpose of the Study:

• To demonstrate the creation of an intrinsic 1T’ MoTe2 lattice using a novel terahertz pulse irradiation method.
• To resolve the long-standing debate regarding light-induced polymorphic transitions in MoTe2.
• To highlight the capability of strong-field terahertz pulses in manipulating quantum materials.

Main Methods:

• Irradiation of mono- or few-layer 2H-MoTe2 with a single field-enhanced terahertz pulse.
• Development and application of a single-shot terahertz-pump-second-harmonic-probe technique.
• Utilizing the low photon energy of terahertz pulses to minimize structural damage.

Main Results:

• Successful creation of an intrinsic 1T’ MoTe2 lattice via terahertz pulse irradiation.
• Observation of the phase transition occurring within 10 nanoseconds after photoexcitation.
• Confirmation that the terahertz-induced transition results in a crystalline 1T’ phase, not tellurium clusters.

Conclusions:

• Strong-field terahertz pulses can controllably induce the 2H to 1T’ polymorphic transition in MoTe2.
• This work provides crucial insights resolving the debate on light-induced phase transitions in MoTe2.
• Terahertz technology offers a promising avenue for precise manipulation of quantum materials.