Efficient Charge-Spin Conversion and Magnetization Switching though Rashba Effect at Topological Insulator/Ag Interface

Abstract

We report the observation of efficient charge-to-spin conversion in the three-dimensional topological insulator (TI) Bi2Se3 and Ag bilayer by the spin-torque ferromagnetic resonance technique. The spin orbit torque ratio in the Bi2Se3/Ag/CoFeB heterostructure shows a significant enhancement as the Ag thickness increases to ~2 nm and reaches a value of 0.5 for 5 nm Ag, which is ~3 times higher than that of Bi2Se3/CoFeB at room temperature. The observation reveals the interfacial effect of Bi2Se3/Ag exceeds that of the topological surface states (TSS) in the Bi2Se3 layer and plays a dominant role in the charge-to-spin conversion in the Bi2Se3/Ag/CoFeB system. Based on the first-principles calculations, we attribute our observation to the large Rashba-splitting bands which wrap the TSS band and has the same net spin polarization direction as TSS of Bi2Se3. Subsequently, we demonstrate for the first time the Rashba induced magnetization switching in Bi2Se3/Ag/Py with a low current density of 5.8 X 10^5 A/cm2.

References in corpus (8)

• Strong spin-orbit splitting on Bi surfaces
• Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Determination of intrinsic spin Hall angle in Pt
• Epitaxial growth of topological insulator Bi2Se3 film on Si(111) with atomically sharp interface
• Surface state dominated spin-charge current conversion in topological insulator/ferromagnetic insulator heterostructures
• Observation of inverse spin Hall effect in bismuth selenide
• Rashba-Edelstein Magnetoresistance in Metallic Heterostructure