Exchange Coupling-Induced Spin Dynamic Damping Modulation at the Py/FeMn Interface

Area of Science:

• Spintronics
• Materials Science
• Condensed Matter Physics

Background:

• Spin dynamic damping is critical for advanced magnetic memory, sensors, and logic systems.
• Interfacial antiferromagnetic exchange coupling is a key phenomenon in spintronic heterostructures.

Purpose of the Study:

• To investigate the magneto-dynamics of Ni80Fe20(Py)/Fe50Mn50(FeMn) bilayers.
• To elucidate the role of interfacial exchange coupling versus spin pumping in spin dynamic damping.

Main Methods:

• Systematic investigation of Py/FeMn bilayers with varying FeMn thicknesses.
• Introduction of a Copper (Cu) spacer to decouple magnetic layers.
• Analysis of spin dynamic damping and spin pumping effects.

Main Results:

• An interfacial exchange bias field emerges for FeMn thickness > 5 nm, significantly increasing spin dynamic damping.
• Introducing a Cu spacer suppresses exchange bias and reduces damping, with a minor increase attributed to spin pumping.
• Estimated interfacial spin mixing conductance in Py/Cu/FeMn trilayers is 3.44 nm⁻², linked to FeMn's weak spin-orbit coupling.
• FeMn insertion demonstrates a short spin diffusion length and confirms interfacial exchange coupling's dominant role in damping enhancement.

Conclusions:

• Interfacial exchange coupling is the primary driver of enhanced spin dynamic damping in Py/FeMn bilayers, surpassing the spin pumping effect.
• The exchange coupling at the Py/FeMn interface promotes spin relaxation and hinders spin transmission.
• Integrating antiferromagnetic materials with exchange coupling interfaces offers a promising route to enhance high-frequency spintronic applications.