Inverse quantum spin Hall effect generated by spin pumping from precessing magnetization into a graphene-based two-dimensional topological insulator

Abstract

We propose a multiterminal nanostructure for electrical probing of the quantum spin Hall effect (QSHE) in two-dimensional (2D) topological insulators. The device consists of a ferromagnetic (FM) island with precessing magnetization that pumps (in the absence of any bias voltage) pure spin current symmetrically into the left and right adjacent 2D TIs modeled as graphene nanoribbons with the intrinsic spin-orbit (SO) coupling. The QSH regime of the six-terminal TI|FM|TI nanodevice, attached to two longitudinal and four transverse normal metal electrodes, is characterized by the SO-coupling-induced energy gap, chiral spin-filtered edge states within finite length TI regions, and quantized spin Hall conductance when longitudinal bias voltage is applied, despite the presence of the FM island. The same unbiased device, but with precessing magnetization of the central FM island, blocks completely pumping of total spin and charge currents into the longitudinal electrodes while generating DC transverse charge Hall currents. Although these transverse charge currents are not quantized, their induction together with zero longitudinal charge current is a unique electrical response of TIs to pumped pure spin current that cannot be mimicked by SO-coupled but topologically trivial systems. In the corresponding two-terminal inhomogeneous TI|FM|TI nanostructures, we image spatial profiles of local spin and charge currents within TIs which illustrate transport confined to chiral spin-filtered edges states while revealing concomitantly the existence of interfacial spin and charge currents flowing around TI|FM interfaces and penetrating into the bulk of TIs over some short distance.

11 pages, 8 figures; published expanded version with new figures on spatial profiles of local spin and charge currents

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Cited by in corpus (11)

• Microwave-driven ferromagnet--topological-insulator heterostructures: The prospect for giant spin battery effect and quantized charge pump devices
• Recursive Green's function method for multi-terminal nanostructures
• Graphene-based spin-pumping transistor
• Magnetic AC control of the spin textures in a helical Luttinger liquid
• Emergence of inductance and capacitance from topological electromagnetism
• Dynamical spin-to-charge conversion on the edge of quantum spin Hall insulator
• Semi-Quantized Spin Pumping and Spin-Orbit Torques in Topological Dirac Semimetals
• Long-range spin transport on the surface of topological Dirac semimetal
• Quantum transport by spin-polarized edge states in graphene nanoribbons in the quantum spin Hall and quantum anomalous Hall regimes
• Local heat current flow in ballistic phonon transport of graphene nanoribbons
• Chiral edge transport along domain walls in magnetic topological insulator nanoribbons