Crystal symmetry-dependent Orbital Rashba Edelstein effect in epitaxial CuO thin film

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Orbital angular momentum (OAM) manipulation is key for efficient spintronic devices.
• OAM generation is typically linked to electron orbital hopping and hybridization.
• Anisotropic OAM responses in crystalline systems are influenced by crystal symmetry.

Purpose of the Study:

• Investigate the role of crystal symmetry in OAM-related phenomena.
• Explore the orbital Rashba-Edelstein effect in crystalline materials.
• Demonstrate symmetry-dependent spin torque efficiency in CuO thin films.

Main Methods:

• Epitaxial growth of CuO thin films with four-fold crystal symmetry.
• Experimental verification using second harmonic Hall measurements.
• First-principles calculations to understand electronic structure and effects.

Main Results:

• Observed a crystal-symmetry-dependent sign change in spin torque efficiency in CuO/ferromagnetic heterostructures.
• Confirmed a strong four-fold anisotropy of the orbital Rashba-Edelstein effect in crystalline CuO.
• Experimental and computational evidence highlights crystal symmetry's impact on OAM anisotropy.

Conclusions:

• Crystal symmetry is a critical factor in governing the anisotropy of OAM-related responses.
• The study provides a symmetry-based framework for designing orbitronic functionalities.
• Findings pave the way for advanced spintronic devices with tailored magnetic manipulation.