Ultra-efficient spin-orbit torque induced magnetic switching in W/CoFeB/MgO structures

Area of Science:

• Spintronics
• Materials Science
• Condensed Matter Physics

Background:

• Spin-orbit torque (SOT) is a key mechanism for energy-efficient magnetic switching in spintronic devices.
• Perpendicular magnetic anisotropy (PMA) in heavy metal/ferromagnet heterostructures is crucial for device performance.

Purpose of the Study:

• To investigate SOT-induced magnetic switching in W/CoFeB/MgO structures.
• To determine the critical current density for efficient SOT switching.
• To elucidate the physical mechanisms behind ultra-efficient switching.

Main Methods:

• Fabrication of W/CoFeB/MgO heterostructures.
• Measurement of SOT-induced magnetic switching.
• Utilizing high-resolution Kerr microscopy for direct observation of the switching process.
• Analysis of domain wall pinning fields and spin Hall angles.

Main Results:

• Achieved a critical current density as low as 1.15 × 10^6 A cm^-2 for SOT-induced switching.
• Demonstrated ultra-efficient magnetic switching attributed to high spin Hall angle of W and low domain wall pinning in CoFeB.
• Directly observed the SOT switching procedure using Kerr microscopy.
• Identified weak Dzyaloshinsky-Moriya interactions as favorable for switching.

Conclusions:

• W/CoFeB/MgO structures exhibit ultra-efficient SOT-induced magnetic switching.
• The study provides a physical explanation for the observed efficiency, highlighting the roles of material properties.
• Direct observation of the switching dynamics enhances understanding and promotes SOT-based memory device research.