Valley-Hall alternatively changing conductivity in gapped and strained graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Graphene/h-BN heterostructures exhibit unique electronic properties due to proximity effects.
• The valley-Hall effect is crucial for understanding electron transport in low-dimensional materials.

Purpose of the Study:

• Investigate the alternatively changing (ac) valley-Hall effect in graphene/h-BN under external fields.
• Analyze the influence of electric, magnetic, and light fields on electronic properties.

Main Methods:

• Derived the ac conductivity tensor (σ) using the Boltzmann equation.
• Incorporated orbital magnetic moment, Berry curvature, and anisotropic Berry curvature dipole into calculations.
• Analyzed the effects of static electric (E₀), magnetic (B₀), and light (E<0xE2><0x82><0x90>₁) fields.

Main Results:

• Observed net ac Hall conductivity when B₀ ≠ 0 due to valley-dependent conductivity amplitudes.
• Demonstrated that ac Hall conductivities and optical gain are tunable by E₀ amplitude and direction.
• Showcased valley-resolved and nonlinear dependence of conductivity on chemical potential.

Conclusions:

• External fields offer precise control over the ac valley-Hall effect in graphene/h-BN.
• The findings provide a pathway for manipulating electronic and optical properties in 2D materials.
• This research contributes to the development of novel electronic and optoelectronic devices.