Berry Curvature-Driven Valley Nernst Effect in Monolayer WSe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Berry curvature in Dirac cones drives anomalous transport phenomena like the Hall and Nernst effects.
• Detecting Berry curvature in 2D transition metal dichalcogenides (TMDs) requires breaking time-reversal symmetry for valley polarization.
• Direct observation and control of valley polarization in 2D TMDs are challenging for practical applications.

Purpose of the Study:

• To experimentally verify the Berry curvature-driven Valley Nernst effect (VNE) in interlayer TMDs.
• To investigate VNE in monolayer (ML) WSe2 within a Pt/YIG bilayer structure.
• To explore new pathways for generating spin- and valley-current-based thermoelectric devices.

Main Methods:

• Experimental measurements of VNE signals in a Pt/YIG bilayer structure with ML WSe2.
• Theoretical calculations to confirm the origin of VNE signals.
• Utilizing the unique properties of WSe2 and the Pt/YIG heterostructure.

Main Results:

• First experimental verification of the Berry curvature-driven VNE in interlayer TMDs.
• Demonstrated that VNE signals in ML WSe2 are driven by its high Berry curvature.
• Established a link between Berry curvature and thermoelectric phenomena in 2D materials.

Conclusions:

• The study provides experimental evidence for the Berry curvature-driven VNE in ML WSe2.
• This work opens avenues for developing novel thermoelectric devices based on spin and valley currents.
• The findings contribute to a deeper understanding of anomalous transport in 2D materials.