High Spin to Charge Conversion Efficiency in Electron Beam-Evaporated Topological Insulator Bi₂Se₃

Abstract

Bi 2 Se 3 is a well-established topological insulator (TI) having spin momentum locked Dirac surface states at room temperature and predicted to exhibit high spin to charge conversion efficiency (SCCE) for spintronics applications. The SCCE in TIs is characterized by an inverse Edelstein effect length (λ IREE ). We report an λ IREE of ∼0.36 nm, which is the highest ever observed in Bi 2 Se 3 . Here, we performed spin pumping and inverse spin Hall effect (ISHE) in an electron beam-evaporated Bi 2 Se 3 / CoFeB bilayer. The Bi 2 Se 3 thickness dependence of λ IREE , perpendicular surface anisotropy (K S ), spin mixing conductance, and spin Hall angle confirmed that spin to charge conversion is due to spin momentum locked Dirac surface states. We propose that the role of surface states in SCCE can be understood by the evaluation of K S . The SCCE is found to be high when the value of K S is small.

Detection and Control of the Effective Magnetic Field in a Ca‐Doped Bi2Se3 Topological Insulator

“…This work demonstrates promising results for gate‐controlled spin polarization and suggests a novel method for measuring spin polarization in a TI quantitatively. The research group has shown the thickness dependence of spin pumping and spin Hall effect in TI channel at room temperature, [ 49 ] which suggests the possible application to electronic devices. In principle, our method is valid at room temperature and therefore our work should be useful for characterizing new spintronic materials and developing spintronic devices.…”

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

“…The details of the set-up can also be found elsewhere. 10,[13][14][15][16][17][18][19][20] 3 Results and discussion Resonance field (H res ) and linewidth (DH) are evaluated from the ferromagnetic resonance spectra. The FMR data (see Fig.…”

Spin pumping and inverse spin Hall effect in CoFeB/IrMn heterostructures

“…ISHE measurements have been performed by connecting a nanovoltmeter over two ends of the sample (sample size: 3 mm × 2 mm). The details of the ISHE set-up can be found elsewhere [11,12,[23][24][25][26][27][28].…”