Large Chiral Orbital Texture and Orbital Edelstein Effect in Co/Al Heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Recent experiments observed significant torque enhancement in Co/Pt heterostructures with an inserted Al layer.
• This enhancement suggested a Rashba-like interaction at the metallic Cobalt/Aluminum interface.
• Understanding interfacial phenomena is crucial for developing advanced magnetic devices.

Purpose of the Study:

• To theoretically investigate the origin of the large torques observed in Co/Al interfaces.
• To elucidate the role of orbital texture and Rashba effects in current-induced torques.
• To provide a theoretical foundation for experimental findings and advance orbital transport phenomena.

Main Methods:

• First-principles calculations were employed to analyze the electronic structure at the Co/Al interface.
• Analysis focused on the emergence and characteristics of orbital textures in reciprocal space.
• The contributions of orbital Rashba effect and spin-orbit coupling were quantified.

Main Results:

• A large helical orbital texture was revealed in the interfacial Cobalt layer, originating from the orbital Rashba effect.
• Surface states at the Co/Al interface were identified as the source of this orbital texture.
• Spin-orbit coupling contributes less significantly, with higher-order winding of orbital moments.

Conclusions:

• The helical orbital texture leads to a nonequilibrium orbital accumulation, generating substantial current-induced torques.
• This study provides essential theoretical support for experimental observations in Co/Al systems.
• The findings highlight the potential of orbital transport phenomena in all-metallic magnetic systems utilizing light elements.