Spin-torque generator engineered by natural oxidation of Cu

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• The spin Hall effect (SHE) is a spin-orbit coupling phenomenon crucial for generating and detecting spin currents.
• SHE enables electric manipulation of magnetization via spin torque, essential for spintronic devices.
• Heavy metals were previously considered essential for efficient spin-torque generation.

Purpose of the Study:

• To investigate the potential of light metals, specifically copper (Cu), for spin-torque generation.
• To explore the role of natural oxidation in enhancing the spin Hall effect in copper.
• To demonstrate efficient spin-torque generation in a copper-based heterostructure.

Main Methods:

• Fabrication of Cu/Ni₈₁Fe₁₉ bilayers.
• Controlled tuning of surface oxidation on copper.
• Measurement of spin-torque generation efficiency.

Main Results:

• Significant enhancement of the spin Hall effect in naturally oxidized copper.
• Spin-torque generation efficiency in Cu/Ni₈₁Fe₁₉ bilayers increased by over two orders of magnitude.
• Achieved spin-torque generation efficiency comparable to that of platinum/ferromagnetic metal bilayers.

Conclusions:

• Natural oxidation plays a critical role in enhancing the spin Hall effect in light metals like copper.
• This finding challenges the necessity of heavy metals for efficient spin-torque generators.
• Opens new avenues for engineering spintronic devices through oxygen control, enabling magnetization manipulation without heavy metals.