Valley filtering by a line-defect in graphene: quantum interference and inversion of the filter effect

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Valley filters are essential components in devices utilizing the valley degree of freedom in materials.
• Graphene's unique electronic properties make it a promising material for spintronic and valleytronic applications.

Purpose of the Study:

• To analyze the mechanism of valley filtering caused by a line defect in graphene.
• To investigate methods for inverting valley filtering using external stimuli.
• To understand the role of Fano resonances in graphene's transport properties.

Main Methods:

• Atomistic modeling to simulate valley filtering.
• Mode decomposition applied to a tight-binding model.
• Analysis of k-space transport channels and band structure.
• Investigation of gate voltage effects on carrier occupation.

Main Results:

• A destructive interference effect, specifically a Fano resonance/antiresonance, was identified on the p-side of the Dirac point, leading to reduced conductance.
• Valley filtering can be reversed by altering carrier occupations with a gate voltage.
• The reversal mechanism is attributed to a valley-dependent Fano resonance splitting.

Conclusions:

• The study provides a detailed understanding of valley filtering mechanisms in graphene line defects.
• External control over valley filtering is achievable, opening possibilities for advanced graphene-based devices.
• Results pave the way for enhanced control of valley transport in future electronic applications.