Current-induced switching of proximity-induced ferromagnetic surface states in a topological insulator

AbstractElectrical manipulation of magnetization could be an essential function for energy-efficient spintronics technology. A magnetic topological insulator, possessing a magnetically gapped surface state with spin-polarized electrons, not only exhibits exotic topological phases relevant to the quantum anomalous Hall state but also enables the electrical control of its magnetic state at the surface. Here, we demonstrate efficient current-induced switching of the surface ferromagnetism in hetero-bilayers consisting of the topological insulator (Bi1-xSbx)2Te3 and the ferromagnetic insulator Cr2Ge2Te6, where the proximity-induced ferromagnetic surface states play two roles: efficient charge-to-spin current conversion and emergence of large anomalous Hall effect. The sign reversal of the surface ferromagnetic states with current injection is clearly observed, accompanying the nearly full magnetization reversal in the adjacent insulating Cr2Ge2Te6 layer of an optimal thickness range. The present results may facilitate an electrical control of dissipationless topological-current circuits.

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Direct observation of spin-polarized surface states in the parent compound of a topological insulator using spin- and angle-resolved photoemission spectroscopy in a Mott-polarimetry mode

New Journal of Physics ◽

10.1088/1367-2630/12/12/125001 ◽

2010 ◽

Vol 12 (12) ◽

pp. 125001 ◽

Cited By ~ 23

Author(s):

D Hsieh ◽

L Wray ◽

D Qian ◽

Y Xia ◽

J H Dil ◽

...

Keyword(s):

Direct Observation ◽

Topological Insulator ◽

Parent Compound ◽

Surface States ◽

Photoemission Spectroscopy ◽

Angle Resolved Photoemission Spectroscopy ◽

Spin Polarized ◽

Polarized Surface

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Topological insulator metamaterial with giant circular photogalvanic effect

Science Advances ◽

10.1126/sciadv.abe5748 ◽

2021 ◽

Vol 7 (14) ◽

pp. eabe5748

Author(s):

X. Sun ◽

G. Adamo ◽

M. Eginligil ◽

H. N. S. Krishnamoorthy ◽

N. I. Zheludev ◽

...

Keyword(s):

Topological Insulator ◽

Structural Design ◽

Surface States ◽

Optical Excitation ◽

Fold Increase ◽

Photogalvanic Effect ◽

Spin Electronics ◽

Spin Polarized ◽

Polarized Surface ◽

Spin Momentum

One of the most notable manifestations of electronic properties of topological insulators is the dependence of the photocurrent direction on the helicity of circularly polarized optical excitation. The helicity-dependent photocurrents, underpinned by spin-momentum locking of surface Dirac electrons, are weak and easily overshadowed by bulk contributions. Here, we show that the chiral response can be enhanced by nanostructuring. The tight confinement of electromagnetic fields in the resonant nanostructure enhances the photoexcitation of spin-polarized surface states of topological insulator Bi1.5Sb0.5Te1.8Se1.2, leading to an 11-fold increase of the circular photogalvanic effect and a previously unobserved photocurrent dichroism (ρcirc = 0.87) at room temperature. The control of spin transport in topological materials by structural design is a previously unrecognized ability of metamaterials that bridges the gap between nanophotonics and spin electronics, providing opportunities for developing polarization-sensitive photodetectors.

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Generation, transport, and detection of valley-coupled spin-polarized electrons in WSe2-graphene-topological insulator heterostructure devices

Conference on Lasers and Electro-Optics ◽

10.1364/cleo_qels.2017.ff2f.7 ◽

2017 ◽

Author(s):

Soonyoung Cha ◽

Doeon Lee ◽

Je-Hyun Kim ◽

Minji Noh ◽

Hyemin Bae ◽

...

Keyword(s):

Topological Insulator ◽

Polarized Electrons ◽

Spin Polarized ◽

Heterostructure Devices

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Inverse spin Hall effect in heterostructures “nanostructured ferromagnet/topological insulator”

EPJ Web of Conferences ◽

10.1051/epjconf/201818501005 ◽

2018 ◽

Vol 185 ◽

pp. 01005

Author(s):

P.N. Petrov ◽

M.D. Davydova ◽

P.N. Skirdkov ◽

K.A. Zvezdin ◽

J.G. Lin ◽

...

Keyword(s):

Hall Effect ◽

Topological Insulator ◽

Electronic Transport ◽

Spin Current ◽

Spin Hall Effect ◽

Magnetization Dynamics ◽

Micromagnetic Simulations ◽

Dc Voltage ◽

Spin Polarized ◽

Inverse Spin Hall Effect

Interaction between magnetization dynamics and spin polarized electronic transport has been studied for ferromagnet nanodisk situated upon a 3D topological insulator (TI) film. Resonant magnetization dynamics leads to generation of spin current, which flows into the topological insulator, where spin to charge conversion occurs. Using micromagnetic simulations for magnetization dynamics we estimate the dc voltage, which is created due to this process in topological insulator. Contribution from different modes, which are characteristic for nanodisks, to the voltage was calculated.

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Anisotropy effects on Rashba and topological insulator spin-polarized surface states: A unified phenomenological description

Physical Review B ◽

10.1103/physrevb.84.155453 ◽

2011 ◽

Vol 84 (15) ◽

Cited By ~ 27

Author(s):

Emmanouil Frantzeskakis ◽

Marco Grioni

Keyword(s):

Topological Insulator ◽

Surface States ◽

Phenomenological Description ◽

Spin Polarized ◽

Polarized Surface

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Experimental observation of the spin Hall effect using electronic nonlocal detection

10.1093/oso/9780198787075.003.0014 ◽

2017 ◽

Author(s):

S. O. Valenzuela ◽

T. Kimura

Keyword(s):

Hall Effect ◽

Anomalous Hall Effect ◽

Electrical Signal ◽

Spin Hall Effect ◽

Optical Injection ◽

Spin Accumulation ◽

Polarized Electrons ◽

Ferromagnetic Electrodes ◽

Spin Polarized ◽

Electronic Detection

This chapter shows how the spin Hall effect (SHE) has been described as a source of spin-polarized electrons for electronic applications without the need for ferromagnets or optical injection. Because spin accumulation does not produce an obvious measurable electrical signal, electronic detection of the SHE proved to be elusive and was preceded by optical demonstrations. Several experimental schemes for the electronic detection of the SHE had been originally proposed, including the use of ferromagnetic electrodes to determine the spin accumulation at the edges of the sample. However, the difficulty of sample fabrication and the presence of spin-related phenomena such as anisotropic magnetoresistance or the anomalous Hall effect in the ferromagnetic electrodes could mask or even mimic the SHE signal in the sample layouts.

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Optically Induced and Detected Spin Current

10.1093/oso/9780198787075.003.0006 ◽

2017 ◽

Cited By ~ 1

Author(s):

A. Hirohata ◽

J.-Y. Kim

Keyword(s):

Band Gap ◽

Polarized Light ◽

Spin Current ◽

Polarized Electrons ◽

Circularly Polarized Light ◽

Circularly Polarized ◽

Spin Polarized ◽

Electron Hole Pair ◽

Tunnelling Microscopy ◽

Optically Induced

This chapter presents an alternative method of injecting spin-polarized electrons into a nonmagnetic semiconductor through photoexcitation. This method uses circularly-polarized light, whose energy needs to be the same as, or slightly larger than, the semiconductor band-gap, to excite spin-polarized electrons. This process will introduce a spin-polarized electron-hole pair, which can be detected as electrical signals. Such an optically induced spin-polarized current can only be generated in a direct band-gap semiconductor due to the selection rule described in the following sections. This introduction of circularly polarized light can also be used for spin-polarized scanning tunnelling microscopy.

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