Enhanced Spin-Orbit Coupling in Heavy Metals via Molecular Coupling.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• 5d metals are crucial in electronics due to strong spin-orbit coupling (SOC), enabling efficient spin-electric conversion.
• Fullerene (C₆₀) layers alter metal electronic structures via hybridization and charge transfer.

Purpose of the Study:

• To investigate the impact of C₆₀ on the spin-dependent transport properties of 5d metals.
• To quantify changes in spin Hall magnetoresistance and anisotropic magnetoresistance.
• To explore the potential for dynamic SOC modification in thin metal films.

Main Methods:

• Experimental measurement of spin Hall magnetoresistance (SMR) and anisotropic magnetoresistance (AMR) for Pt/C₆₀ and Ta/C₆₀ heterostructures.
• Noncollinear density functional theory (DFT) calculations to model SOC enhancement and electronic interactions.

Main Results:

• SMR in Pt/C₆₀ and Ta/C₆₀ was up to 6 times higher than pristine metals, indicating a 20-60% increase in the spin Hall angle.
• C₆₀ presence increased anisotropic magnetoresistance by up to 700% at low magnetic fields (1-30 mT).
• DFT calculations confirmed significant SOC enhancement by C₆₀, penetrating the metal layer and correlating with magnetic moment changes.

Conclusions:

• C₆₀ molecular layers can substantially enhance the spin-orbit coupling of 5d metals.
• The observed effects can be dynamically controlled via gating, suggesting tunable SOC properties.
• This provides a pathway for developing advanced spintronic devices, including spin-transfer torque memories and pure spin current circuits.