Spin Hall effect originated from fractal surface.

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• The spin Hall effect (SHE) is crucial for spintronics and magnonics.
• SHE arises from spin-orbit coupling (SOC) and is influenced by surface roughness.
• Understanding SHE in materials with small SOC is essential.

Purpose of the Study:

• To theoretically investigate the impact of correlated surface roughness on SHE in metallic thin films with low SOC.
• To explore how surface roughness parameters influence SHE magnitude and mechanisms.

Main Methods:

• Utilized a theoretical approach based on the Born approximation.
• Modeled self-affine fractal surfaces using the k-correlation model.
• Characterized surface roughness by exponent H, correlation length ξ, and amplitude δ.

Main Results:

• The spin Hall angle increased by two orders of magnitude as H decreased from 1 to 0.
• For Gaussian surface profiles, side jump scattering dominated SHE.
• Non-Gaussian profiles indicated contributions from both side jump and skew scatterings.

Conclusions:

• Surface roughness details, particularly the roughness exponent, can significantly adjust SHE in non-heavy metals.
• The findings highlight the role of surface morphology in tuning spintronic properties.
• This work provides insights into controlling SHE through surface engineering.