Magnetization switching of multi-state magnetic structures with current-induced torques.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Spintronic devices demand precise control over magnetic configurations at the sub-micron level.
• Heavy metal/ferromagnetic heterostructures offer a pathway via spin-orbit torques (SOTs) generated by current flow.
• Conventional SOT switching typically targets uniform magnetic states in materials with uniaxial anisotropy.

Purpose of the Study:

• To investigate the switching of magnetization in tantalum/nickel-iron (Ta/NiFe) heterostructures using SOTs.
• To explore switching in structures exhibiting both uniaxial and biaxial anisotropy, including non-uniform magnetic states.
• To demonstrate the potential for multi-level magnetic memory applications.

Main Methods:

• Fabrication of Ta/NiFe heterostructures with shape-induced uniaxial and biaxial magnetic anisotropy.
• Application of spin-orbit torques generated by current in the heavy metal layer.
• Monitoring of magnetic states using the planar Hall effect (PHE).

Main Results:

• Successfully switched magnetization in Ta/NiFe heterostructures using SOTs.
• Demonstrated control over both uniform (uniaxial) and non-uniform (biaxial) magnetic configurations.
• Confirmed the influence of anisotropy type on magnetic switching behavior.

Conclusions:

• Spin-orbit torque switching is effective for both uniaxial and biaxial anisotropy in Ta/NiFe heterostructures.
• The ability to control non-uniform magnetization states is crucial for advanced memory concepts.
• These findings support the development of multi-level magnetic memory devices utilizing SOT switching.