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

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Masataka Mogi ◽  
Kenji Yasuda ◽  
Reika Fujimura ◽  
Ryutaro Yoshimi ◽  
Naoki Ogawa ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Spin Current ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Polarized Electrons ◽  
Electrical Control ◽  
Spin Polarized ◽  
Topological Current ◽  
Efficient Charge ◽  
Electrical Manipulation

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.

scholarly journals Topological insulator metamaterial with giant circular photogalvanic effect

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.

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

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.

Experimental observation of the spin Hall effect using electronic nonlocal detection

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.

Optically Induced and Detected Spin Current

2017 ◽  
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.

SURFACE AND THIN FILM MAGNETISM WITH SPIN POLARIZED ELECTRONS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-9-C8-16 ◽  
Author(s):  
H. C. Siegmann ◽  
D. Mauri ◽  
D. Scholl ◽  
E. Kay
Keyword(s):  
Thin Film ◽  
Polarized Electrons ◽  
Spin Polarized ◽  
Thin Film Magnetism

scholarly journals Anomalous Hall effect in a magnetically extended topological insulator heterostructure

2020 ◽  
Vol 4 (9) ◽  
Author(s):  
Nan Liu ◽  
Xuefan Niu ◽  
Yuxin Liu ◽  
Qinghua Zhang ◽  
Lin Gu ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Insulator ◽  
Anomalous Hall Effect
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