Spin-orbit torque magnetometry by wide-field magneto-optical Kerr effect

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spintronics

Background:

• Magneto-optical Kerr effect (MOKE) is crucial for probing surface magnetism in thin films.
• Characterizing spin-orbit torque (SOT) is essential for developing spintronic devices.
• Current-induced damping-like SOT (DL-SOT) influences magnetic switching.

Purpose of the Study:

• To present a wide-field MOKE technique for characterizing DL-SOT.
• To apply this technique to micron-sized and unpatterned magnetic heterostructures.
• To quantify DL-SOT efficiency in Ta-based heterostructures.

Main Methods:

• Utilized a wide-field MOKE setup with Köhler illumination.
• Analyzed current-induced hysteresis loop shifts.
• Investigated Ta-based heterostructures in various geometries (bar, Hall-cross, unpatterned).

Main Results:

• Successfully characterized DL-SOT in magnetic heterostructures.
• Quantified the DL-SOT efficiency in Ta-based samples to be approximately |ξ_DL| ≈ 0.08.
• Demonstrated the technique's applicability to different sample geometries.

Conclusions:

• The proposed wide-field MOKE technique provides direct and instant DL-SOT characterization.
• This method eliminates the need for complex electrical signal interpretation.
• It is a valuable tool for spintronic research and device development.