Spin-orbit torque driven magnetization switching in W/CoFeB/MgO-based type-Y three terminal magnetic tunnel junctions

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Current-induced magnetization switching is crucial for magnetic memory devices.
• Spin-orbit torque (SOT) offers a promising mechanism for efficient switching.
• Understanding SOT in realistic device structures is essential for technological advancement.

Purpose of the Study:

• To investigate current-induced magnetization switching in W/CoFeB/MgO magnetic tunnel junctions.
• To evaluate SOT-driven switching in a type-Y device geometry.
• To compare experimental results with existing theoretical models.

Main Methods:

• Fabrication and characterization of three-terminal W/CoFeB/MgO magnetic tunnel junctions.
• Measurement of critical switching current (Ic) under varying magnetic fields.
• Analysis of switching probability dependence on field and current pulse duration (DC vs. 50 ns).

Main Results:

• Estimated effective spin Hall angle of approximately 0.07.
• Field and DC current-induced switching aligns with the thermally assisted magnetization switching model.
• Significant deviation observed for 50 ns pulse current switching, even with field-like torque considered.

Conclusions:

• The conventional thermally assisted magnetization switching model is insufficient for describing SOT-induced switching with short pulses.
• Short pulse SOT switching exhibits dynamics not captured by standard models.
• This suggests new physical mechanisms governing SOT switching under transient conditions.