Switching of Charge-Current-Induced Spin Polarization in the Topological Insulator BiSbTeSe2

Abstract

The charge-current-induced spin polarization is a key property of topological insulators for their applications in spintronics. However, topological surface states are expected to give rise to only one type of spin polarization for a given current direction, which has been a limiting factor for spin manipulations. Here we report that in devices based on the bulk-insulating topological insulator BiSbTeSe2, an unexpected switching of spin polarization was observed upon changing the chemical potential. The spin polarization expected from the topological surface states was detected in a heavily electron-doped device, whereas the opposite polarization was reproducibly observed in devices with low carrier densities. We propose that the latter type of spin polarization stems from topologically-trivial two-dimensional states with a large Rashba spin splitting, which are caused by a strong band bending at the surface of BiSbTeSe2 beneath the ferromagnetic electrode used as a spin detector. This finding paves the way for realizing the "spin transistor" operation in future topological spintronic devices.

11 pages, 8 figures (paper proper) + 3 pages, 4 figures (Supplemental Material); rebuttal against recent criticisms towards topological-insulator spin-detection experiments has been substantiated; accepted for publication in PRB

References in corpus (11)

• Electrical Detection of Spin Transport in Lateral Ferromagnet-Semiconductor Devices
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Emergent quantum confinement at topological insulator surfaces
• Observation of inverse spin Hall effect in bismuth selenide
• Electrical detection of the spin polarization due to charge flow in the surface state of the topological insulator Bi_1.5 Sb_0.5 Te_1.7 Se_1.3
• Spin-transfer torque and spin-polarization in topological-insulator/ferromagnet vertical heterostructures
• Current-induced spin polarization in topological insulator-graphene heterostructures
• Towards the understanding of the origin of charge-current-induced spin voltage signals in the topological insulator Bi${}_2$Se${}_3$
• Top gating of epitaxial (Bi_{1-x}Sb_x)2Te3 topological insulator thin films
• Topological Surface States Originated Spin-Orbit Torques in Bi2Se3
• Interpreting current-induced spin polarization in topological insulator surface states

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• Tunneling Planar Hall Effect in Topological Insulators: Spin-Valves and Amplifiers
• Phonon mode calculations and Raman spectroscopy of the bulk-insulating topological insulator BiSbTeSe${}_2$
• Work function of bulk-insulating topological insulator Bi2-xSbxTe3-ySey
• Origin and evolution of surface spin current in topological insulators
• Bulk and surface spin conductivity in topological insulators with hexagonal warping
• Magnetic proximity effect of a topological insulator and a ferromagnet in thin film bilayers of $BiSbT{e}_3$ and $SrRu{O}_3$
• Transmission Line Model for Materials with Spin-Momentum Locking
• Topological insulator spin transistor
• Topological nature of higher-order hinge states revealed by spin transport
• Unified Framework for Charge-Spin Interconversion in Spin-Orbit Materials
• Opposite current-induced spin polarizations in bulk-metallic Bi2Se3 and bulk-insulating Bi2Te2Se topological insulator thin flakes
• Versatile Large-Area Custom-Feature van der Waals Epitaxy of Topological Insulators
• Charge-induced artifacts in non-local spin transport measurements: How to prevent spurious voltage signals
• Nonlinear spin and orbital Edelstein effect in WTe2
• Detection of current induced spin polarization in epitaxial Bi${}_2$Te${}_3$ thin film
• Strongly suppressed superconducting proximity effect and ferromagnetism in trilayers of $\mathrm{B}{\mathrm{i}}_2\mathrm{S}{\mathrm{e}}_3$ / $\mathrm{SrRu}{\mathrm{O}}_3$ / underdoped $\mathrm{YB}{\mathrm{a}}_2\mathrm{C}{\mathrm{u}}_3{\mathrm{O}}_{\mathrm{x}}$: A possible new platform for Majorana nano-electronics
• Facilitating field-free perpendicular magnetization switching with a Berry curvature dipole in a Weyl semimetal
• The influence of anisotropic Rashba spin-orbit coupling on current-induced spin polarization in graphene
• Correspondence: Reply to "On the understanding of current-induced spin polarization of 3D topological insulators"
• Tracing Dirac points of topological surface states by ferromagnetic resonance
• Promoted current-induced spin polarization in inversion symmetry broken topological insulator thin films
• Robust topological insulator surface state in MBE grown (Bi_{1-x}Sb_x)_2Se_3