Perfect Spin-filtering in graphene monolayer-bilayer superlattice with zigzag boundaries

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Graphene's unique electronic properties make it a promising material for spintronic applications.
• Understanding magnetization at interfaces is crucial for designing novel electronic devices.
• Zigzag edges in graphene structures exhibit distinct electronic and magnetic behaviors.

Purpose of the Study:

• To investigate the formation of spontaneous magnetization at the zigzag boundary of monolayer and bilayer graphene.
• To explore the spin polarization characteristics in graphene superlattices with zigzag boundaries.
• To elucidate the physical mechanisms governing spin-polarized transport in these systems.

Main Methods:

• Self-consistent calculations based on the Hubbard model were employed.
• Analysis of spin-split band structure.
• Investigation of wave-function distribution for electron and hole subbands.

Main Results:

• Spontaneous magnetization is confirmed at the zigzag boundary between monolayer and bilayer graphene.
• Nearly 100% spin polarization is observed in the energy window around the Dirac point.
• Spin polarization is independent of the parallel or antiparallel magnetization configuration at the two boundaries.

Conclusions:

• Low-energy transport is predominantly influenced by magnetization at a single edge, explaining the high spin polarization.
• The observed phenomena are attributed to the spin-split band structure and specific wave-function distributions.
• This study provides fundamental insights into spin control in graphene-based heterostructures.