Spin rectification by orbital polarization in Bi-bilayer nanoribbons

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Physics

Background:

• Quantum spin-Hall (QSH) phase materials exhibit unique edge states with potential for spintronics.
• Bismuth (Bi) based materials are promising candidates for realizing the QSH effect.
• Low-dimensional nanostructures offer tunable electronic properties.

Purpose of the Study:

• Investigate the edge states of Bi(111) bilayer nano-ribbons (BNRs) in the quantum spin-Hall phase.
• Explore the spin-rectifying effect in these BNRs.
• Assess the potential of BNRs for spintronic device applications.

Main Methods:

• First-principles calculations were employed to model the electronic structure.
• A non-equilibrium transport method was utilized to simulate current flow.
• Analysis focused on edge state interactions, spin texture, and geometrical deformation effects.

Main Results:

• The helical edge states in BNRs show tunable interactions based on passivation, enabling valley engineering of Dirac cones.
• Spin texture of Dirac states is significantly influenced by edge passivation, external electric fields, and geometric deformations.
• Curved BNRs demonstrate a spin-valve effect, rectifying electric currents via edge states.

Conclusions:

• Bi(111) BNRs exhibit tunable electronic and spin properties crucial for spintronics.
• Geometric deformation, particularly curvature, is key to achieving spin rectification.
• These findings offer a practical pathway for developing novel spintronic devices using 2D topological insulators.