Spin dynamics and inverse spin Hall effect study in the metallic Pt/NiMn/CoFeB system

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Pure spin current generation is crucial for spintronic devices.
• Spin pumping and Inverse Spin Hall Effect (ISHE) are key mechanisms for spin current studies.
• Antiferromagnetic materials offer potential as alternatives to heavy metals in spintronic heterostructures.

Purpose of the Study:

• Investigate the impact of antiferromagnetic Ni$_{50}$Mn$_{50}$ layers on spin pumping and ISHE.
• Analyze spin current propagation across Pt/NiMn/Co$_{40}$Fe$_{40}$B$_{20}$ interfaces.
• Evaluate changes in Gilbert damping with the incorporation of NiMn.

Main Methods:

• Fabrication of Ta/Pt/Ni$_{50}$Mn$_{50}$ (t nm)/Co$_{40}$Fe$_{40}$B$_{20}$/Ta thin-film heterostructures with varying NiMn thickness (t=0-40 nm).
• Measurement of spin pumping voltage and Inverse Spin Hall Effect.
• Characterization of magnetic properties, including Gilbert damping coefficient (α).

Main Results:

• Finite spin pumping was observed in all fabricated samples.
• Introduction of NiMn reduced spin pumping voltage by approximately 20% compared to the reference.
• A prominent spin pumping voltage with 40 nm NiMn indicated finite spin current propagation.
• Gilbert damping decreased by about 50% with the addition of the NiMn layer.

Conclusions:

• Antiferromagnetic NiMn layers influence spin current dynamics in FM/HM heterostructures.
• NiMn layers can modulate spin pumping efficiency and enhance spin current propagation.
• The observed reduction in Gilbert damping suggests potential applications in low-dissipation spintronic devices.