Valleytronics in two-dimensional materials with line defect

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Valleytronics leverages the valley degree of freedom in electronic systems for novel functionalities.
• Broken inversion symmetry is crucial for generating pure valley currents.
• Polycrystalline 2D materials, such as graphene and transition metal dichalcogenides, naturally possess broken inversion symmetry due to grain boundaries.

Purpose of the Study:

• To review the fundamental properties of valley degree of freedom across grain boundaries in polycrystalline 2D materials.
• To explore manipulation strategies for valley polarization using electrical, magnetic, and mechanical methods.
• To introduce numerical techniques for analyzing valley transport in these systems.

Main Methods:

• Systematic demonstration of valley properties at grain boundaries.
• Overview of electrical, magnetic, and mechanical manipulation techniques.
• Introduction of the non-equilibrium Green's function technique for theoretical analysis.

Main Results:

• Grain boundaries in polycrystalline 2D materials lead to mismatched Dirac valleys and unique valley transport phenomena.
• Various methods can be employed to manipulate and control valley polarization.
• The non-equilibrium Green's function technique is effective for studying valley transport.

Conclusions:

• Polycrystalline 2D materials are promising platforms for valleytronics due to their inherent broken inversion symmetry.
• Understanding and controlling valley transport at grain boundaries is key to advancing valleytronic devices.
• Further research on grain boundary effects in valleytronics is essential.