Field-free magnetization reversal by spin-Hall effect and exchange bias

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Magnetic random access memory (MRAM) faces challenges with high current densities for writing data as device sizes decrease.
• Spin-orbit torques, particularly the spin-Hall effect (SHE), offer a path to reduce write current densities.
• Current SHE applications for perpendicular magnetization require an in-plane magnetic field, limiting practical implementation.

Purpose of the Study:

• To investigate field-free magnetization reversal using the spin-Hall effect.
• To explore the use of antiferromagnetic materials to enable deterministic switching.
• To understand the spin physics at ferromagnetic/antiferromagnetic interfaces.

Main Methods:

• Fabrication of a Pt/Co/IrMn heterostructure.
• Interface engineering to create in-plane exchange bias.
• Experimental demonstration of magnetization reversal driven by the spin-Hall effect.

Main Results:

• Achieved field-free magnetization reversal in a perpendicularly magnetized Pt/Co/IrMn structure.
• Demonstrated that in-plane exchange bias enables deterministic switching via SHE.
• Provided insights into the local spin structure at the interface.

Conclusions:

• Field-free switching via SHE is achievable in perpendicularly magnetized systems by utilizing exchange bias.
• This approach removes the need for external magnetic fields, paving the way for more practical MRAM.
• The study enhances understanding of spin dynamics at antiferromagnetic/ferromagnetic interfaces.