Spintronics Based on Topological Insulators

SPIN ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1640001 ◽  
Author(s):  
Yabin Fan ◽  
Kang L. Wang
Keyword(s):  
Topological Insulators ◽  
Spin Injection ◽  
Surface States ◽  
Research Field ◽  
Spin Torque ◽  
Spin Orbit ◽  
Challenges And Opportunities ◽  
Potential Applications ◽  
Topological Surface ◽  
A Charge

Spintronics using topological insulators (TIs) as strong spin–orbit coupling (SOC) materials have emerged and shown rapid progress in the past few years. Different from traditional heavy metals, TIs exhibit very strong SOC and nontrivial topological surface states that originate in the bulk band topology order, which can provide very efficient means to manipulate adjacent magnetic materials when passing a charge current through them. In this paper, we review the recent progress in the TI-based magnetic spintronics research field. In particular, we focus on the spin–orbit torque (SOT)-induced magnetization switching in the magnetic TI structures, spin–torque ferromagnetic resonance (ST-FMR) measurements in the TI/ferromagnet structures, spin pumping and spin injection effects in the TI/magnet structures, as well as the electrical detection of the surface spin-polarized current in TIs. Finally, we discuss the challenges and opportunities in the TI-based spintronics field and its potential applications in ultralow power dissipation spintronic memory and logic devices.

scholarly journals Discovery of a weak topological insulating state and van Hove singularity in triclinic RhBi2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kyungchan Lee ◽  
Gunnar F. Lange ◽  
Lin-Lin Wang ◽  
Brinda Kuthanazhi ◽  
Thaís V. Trevisan ◽  
...  
Keyword(s):  
Time Reversal ◽  
Topological Insulators ◽  
Dirac Point ◽  
Saddle Points ◽  
Surface States ◽  
Van Hove Singularity ◽  
Space Group ◽  
Topological Materials ◽  
Topological Surface ◽  
Optimal Space

AbstractTime reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P$$\bar{1}$$ 1 ¯ , which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (EF). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects.

scholarly journals Spin‐Orbit Torque Switching of a Nearly Compensated Ferrimagnet by Topological Surface States

2019 ◽  
Vol 31 (35) ◽  
pp. 1901681 ◽  
Author(s):  
Hao Wu ◽  
Yong Xu ◽  
Peng Deng ◽  
Quanjun Pan ◽  
Seyed Armin Razavi ◽  
...  
Keyword(s):  
Surface States ◽  
Spin Orbit ◽  
Topological Surface

Giant photoinduced anomalous Hall effect of the topological surface states in three dimensional topological insulators Bi2Te3

2020 ◽  
Vol 116 (14) ◽  
pp. 141603
Author(s):  
Jinling Yu ◽  
Wenyi Wu ◽  
Yumeng Wang ◽  
Kejing Zhu ◽  
Xiaolin Zeng ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Insulators ◽  
Three Dimensional ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Topological Surface

scholarly journals Electronic properties of the topological insulators Bi₂Se₃ and Bi₂Te₃

2021 ◽  
Author(s):  
◽  
Robin Gühne
Keyword(s):  
Electronic Properties ◽  
Single Crystals ◽  
Topological Insulators ◽  
Three Dimensional ◽  
Surface States ◽  
Quantitative Agreement ◽  
Model Systems ◽  
Electronic Spin ◽  
Band Inversion ◽  
A Charge

<p>The three-dimensional topological insulators Bi₂Se₃ and Bi₂Te₃ are model systems of a new class of materials with an insulating bulk and gapless surface states. Their small band gaps and the heavy elements are essential for the topologically non-trivial band structure, but these features are similarly responsible for other remarkable properties, such as their high thermoelectric performance.  This thesis investigates the electronic properties of the topological insulators Bi₂Se₃ and Bi₂Te₃ with a broad range of experimental methods. Ferromagnetism in Mn doped Bi₂Te₃ is shown to disappear under sample sintering. A surprisingly large magnetoresistance and a charge carrier independent change in the sign of the thermopower with increasing Mn content are discussed.¹²⁵Te nuclear magnetic resonance (NMR) of Bi₂Te₃ single crystals suggest an unusual electronic spin susceptibility and complex NMR shifts. The quadrupole interaction of ²⁰⁹Bi nuclei in Bi₂Se₃ single crystals is shown to be a signature of the band inversion in quantitative agreement with first-principle calculations. Furthermore, it is proposed that the strong spin-orbit coupling of conduction electrons causes a non-trivial orientation dependent quadrupole splitting of the ²⁰⁹Bi resonance.</p>

scholarly journals Deep tuning of photo-thermoelectricity in topological surface states

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shouyuan Huang ◽  
Ireneusz Miotkowski ◽  
Yong P. Chen ◽  
Xianfan Xu
Keyword(s):  
Surface State ◽  
Spin Injection ◽  
Three Dimensional ◽  
Polarized Light ◽  
Surface States ◽  
Linear Dispersion ◽  
Circularly Polarized Light ◽  
Spin Polarized ◽  
Topological Surface ◽  
Topological Surface State

Abstract Three-dimensional topological insulators have been demonstrated in recent years, which possess intriguing gapless, spin-polarized Dirac states with linear dispersion only on the surface. The spin polarization of the topological surface states is also locked to its momentum, which allows controlling motion of electrons using optical helicity, i.e., circularly polarized light. The electrical and thermal transport can also be significantly tuned by the helicity-control of surface state electrons. Here, we report studies of photo-thermoelectric effect of the topological surface states in Bi2Te2Se thin films with large tunability using varied gate voltages and optical helicity. The Seebeck coefficient can be altered by more than five times compared to the case without spin injection. This deep tuning is originated from the optical helicity-induced photocurrent which is shown to be enhanced, reduced, turned off, and even inverted due to the change of the accessed band structures by electrical gating. The helicity-selected topological surface state thus has a large effect on thermoelectric transport, demonstrating great opportunities for realizing helicity control of optoelectronic and thermal devices.

scholarly journals Magnetizing topological surface states of Bi2Se3 with a CrI3 monolayer

2019 ◽  
Vol 5 (5) ◽  
pp. eaaw1874 ◽  
Author(s):  
Yusheng Hou ◽  
Jeongwoo Kim ◽  
Ruqian Wu
Keyword(s):  
Density Functional ◽  
Topological Insulators ◽  
Dirac Point ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Spin Splitting ◽  
Topological Feature ◽  
Topological Parameters ◽  
General Rules ◽  
Topological Surface

To magnetize surfaces of topological insulators without damaging their topological feature is a crucial step for the realization of the quantum anomalous Hall effect (QAHE) and remains as a challenging task. Through density functional calculations, we found that adsorption of a semiconducting two-dimensional van der Waals (2D-vdW) ferromagnetic CrI3 monolayer can create a sizable spin splitting at the Dirac point of the topological surface states of Bi2Se3 films. Furthermore, general rules that connect different quantum and topological parameters are established through model analyses. This work provides a useful guideline for the realization of QAHE at high temperatures in heterostructures of 2D-vdW magnetic monolayers and topological insulators.

scholarly journals Electron–hole asymmetry of the topological surface states in strained HgTe

2017 ◽  
Vol 114 (13) ◽  
pp. 3381-3386 ◽  
Author(s):  
Andreas Jost ◽  
Michel Bendias ◽  
Jan Böttcher ◽  
Ewelina Hankiewicz ◽  
Christoph Brüne ◽  
...  
Keyword(s):  
Topological Insulators ◽  
Quantum Hall ◽  
Surface States ◽  
Metallic Surface ◽  
Electron Hole ◽  
Linear Dispersion ◽  
Strong Electron ◽  
Quantum Oscillations ◽  
Strong Deviation ◽  
Topological Surface

Topological insulators are a new class of materials with an insulating bulk and topologically protected metallic surface states. Although it is widely assumed that these surface states display a Dirac-type dispersion that is symmetric above and below the Dirac point, this exact equivalence across the Fermi level has yet to be established experimentally. Here, we present a detailed transport study of the 3D topological insulator-strained HgTe that strongly challenges this prevailing viewpoint. First, we establish the existence of exclusively surface-dominated transport via the observation of an ambipolar surface quantum Hall effect and quantum oscillations in the Seebeck and Nernst effect. Second, we show that, whereas the thermopower is diffusion driven for surface electrons, both diffusion and phonon drag contributions are essential for the hole surface carriers. This distinct behavior in the thermoelectric response is explained by a strong deviation from the linear dispersion relation for the surface states, with a much flatter dispersion for holes compared with electrons. These findings show that the metallic surface states in topological insulators can exhibit both strong electron–hole asymmetry and a strong deviation from a linear dispersion but remain topologically protected.

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