Ferroelectric Rashba semiconductors, AgBiP2X6 (X = S, Se and Te), with valley polarization: an avenue towards electric and nonvolatile control of spintronic devices

Nanoscale ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 5533-5542
Author(s):  
Baozeng Zhou
Keyword(s):  
Hall Effect ◽  
Spin Splitting ◽  
Promising Candidate ◽  
Spintronic Devices ◽  
Spin Direction ◽  
Band Splitting ◽  
Out Of Plane ◽  
Valley Polarization ◽  
Valley Hall Effect ◽  
Spin Fet

Coexistence of Rashba-type spin splitting (in-plane spin direction) and band splitting at the K/K′ valleys (out-of-plane spin direction) makes the FRS AgBiP2Te6 monolayer a promising candidate for 2D spin FET and spin/valley Hall effect devices.

scholarly journals The valley Nernst effect in WSe2

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Minh Tuan Dau ◽  
Céline Vergnaud ◽  
Alain Marty ◽  
Cyrille Beigné ◽  
Serge Gambarelli ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Hall Effect ◽  
Room Temperature ◽  
Nernst Effect ◽  
Spin Pumping ◽  
Ettingshausen Effect ◽  
Valley Polarization ◽  
Resonance Spin ◽  
Valley Hall Effect ◽  
Good Agreement

AbstractThe Hall effect can be extended by inducing a temperature gradient in lieu of electric field that is known as the Nernst (-Ettingshausen) effect. The recently discovered spin Nernst effect in heavy metals continues to enrich the picture of Nernst effect-related phenomena. However, the collection would not be complete without mentioning the valley degree of freedom benchmarked by the valley Hall effect. Here we show the experimental evidence of its missing counterpart, the valley Nernst effect. Using millimeter-sized WSe$${}_{2}$$2 mono-multi-layers and the ferromagnetic resonance-spin pumping technique, we are able to apply a temperature gradient by off-centering the sample in the radio frequency cavity and address a single valley through spin-valley coupling. The combination of a temperature gradient and the valley polarization leads to the valley Nernst effect in WSe$${}_{2}$$2 that we detect electrically at room temperature. The valley Nernst coefficient is in good agreement with the predicted value.

scholarly journals Intrinsic valley polarization and anomalous valley hall effect in single-layer 2H-FeCl2

ChemPhysMater ◽  
2021 ◽  
Author(s):  
Pei Zhao ◽  
Ying Dai ◽  
Hao Wang ◽  
Baibiao Huang ◽  
Yandong Ma
Keyword(s):  
Hall Effect ◽  
Single Layer ◽  
Valley Polarization ◽  
Valley Hall Effect

scholarly journals Giant field-like torque by the out-of-plane magnetic spin Hall effect in a topological antiferromagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kouta Kondou ◽  
Hua Chen ◽  
Takahiro Tomita ◽  
Muhammad Ikhlas ◽  
Tomoya Higo ◽  
...  
Keyword(s):  
Low Power ◽  
Hall Effect ◽  
Spin Hall Effect ◽  
Spin Splitting ◽  
Large Momentum ◽  
Electrical Control ◽  
Perpendicular Magnetization ◽  
Out Of Plane ◽  
Magnetic Spin ◽  
Unique Potential

AbstractSpin-orbit torques (SOT) enable efficient electrical control of the magnetic state of ferromagnets, ferrimagnets and antiferromagnets. However, the conventional SOT has severe limitation that only in-plane spins accumulate near the surface, whether interpreted as a spin Hall effect (SHE) or as an Edelstein effect. Such a SOT is not suitable for controlling perpendicular magnetization, which would be more beneficial for realizing low-power-consumption memory devices. Here we report the observation of a giant magnetic-field-like SOT in a topological antiferromagnet Mn3Sn, whose direction and size can be tuned by changing the order parameter direction of the antiferromagnet. To understand the magnetic SHE (MSHE)- and the conventional SHE-induced SOTs on an equal footing, we formulate them as interface spin-electric-field responses and analyzed using a macroscopic symmetry analysis and a complementary microscopic quantum kinetic theory. In this framework, the large out-of-plane spin accumulation due to the MSHE has an inter-band origin and is likely to be caused by the large momentum-dependent spin splitting in Mn3Sn. Our work demonstrates the unique potential of antiferromagnetic Weyl semimetals in overcoming the limitations of conventional SOTs and in realizing low-power spintronics devices with new functionalities.

scholarly journals Orbital-enhanced warping effect in px,py-derived Rashba spin splitting of monatomic bismuth surface alloy

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Guan-Yu Chen ◽  
Angus Huang ◽  
Yen-Hui Lin ◽  
Chia-Ju Chen ◽  
Deng-Sung Lin ◽  
...  
Keyword(s):  
Density Functional ◽  
Atomic Orbital ◽  
Surface States ◽  
Scanning Tunneling Spectroscopy ◽  
Spin Splitting ◽  
Scanning Tunneling ◽  
Orbital Symmetry ◽  
Spintronic Devices ◽  
Rashba Spin ◽  
Out Of Plane

AbstractSpin-split Rashba bands have been exploited to efficiently control the spin degree of freedom of moving electrons, which possesses a great potential in frontier applications of designing spintronic devices and processing spin-based information. Given an intrinsic breaking of inversion symmetry and sizeable spin–orbit interaction, two-dimensional (2D) surface alloys formed by heavy metal elements exhibit a pronounced Rashba-type spin splitting of the surface states. Here, we have revealed the essential role of atomic orbital symmetry in the hexagonally warped Rashba spin-split surface state of the $$\sqrt 3 \times \sqrt 3 R30^0$$ 3 × 3 R 3 0 0 BiCu2 monatomic alloy by scanning tunneling spectroscopy (STS) and density functional theory (DFT). From dI/dU spectra and calculated band structures, three hole-like Rashba-split bands hybridized from distinct orbital symmetries have been identified in the unoccupied energy region. Because of the hexagonally deformed Fermi surface, quasi-particle interference (QPI) mappings have resolved scattering channels opened from interband transitions of px,py (mj = 1/2) band. In contrast to the s,pz-derived band, the hexagonal warping is predominately accompanied by substantial out-of-plane spin polarization Sz up to 24% in the dispersion of px,py (mj = 1/2) band with an in-plane orbital symmetry.

scholarly journals Ultrafast non-excitonic valley Hall effect in MoS2/WTe2 heterobilayers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jekwan Lee ◽  
Wonhyeok Heo ◽  
Myungjun Cha ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Hall Effect ◽  
Quantitative Information ◽  
Exciton Energy ◽  
Electron Hole ◽  
Kerr Rotation ◽  
Polarized Electrons ◽  
Spatially Resolved ◽  
Long Valley ◽  
Bound Electron ◽  
Valley Hall Effect

AbstractThe valley Hall effect (VHE) in two-dimensional (2D) van der Waals (vdW) crystals is a promising approach to study the valley pseudospin. Most experiments so far have used bound electron-hole pairs (excitons) through local photoexcitation. However, the valley depolarization of such excitons is fast, so that several challenges remain to be resolved. We address this issue by exploiting a unipolar VHE using a heterobilayer made of monolayer MoS2/WTe2 to exhibit a long valley-polarized lifetime due to the absence of electron-hole exchange interaction. The unipolar VHE is manifested by reduced photoluminescence at the MoS2 A exciton energy. Furthermore, we provide quantitative information on the time-dependent valley Hall dynamics by performing the spatially-resolved ultrafast Kerr-rotation microscopy; we find that the valley-polarized electrons persist for more than 4 nanoseconds and the valley Hall mobility exceeds 4.49 × 103 cm2/Vs, which is orders of magnitude larger than previous reports.

scholarly journals Manipulation of hot carrier cooling dynamics in two-dimensional Dion–Jacobson hybrid perovskites via Rashba band splitting

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jun Yin ◽  
Rounak Naphade ◽  
Partha Maity ◽  
Luis Gutiérrez-Arzaluz ◽  
Dhaifallah Almalawi ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Phonon Scattering ◽  
Transient Absorption Spectroscopy ◽  
Band Model ◽  
Two Dimensional ◽  
Spintronic Devices ◽  
Hot Carrier ◽  
Band Splitting ◽  
Perovskite Materials ◽  
Spin Polarized

AbstractHot-carrier cooling processes of perovskite materials are typically described by a single parabolic band model that includes the effects of carrier-phonon scattering, hot phonon bottleneck, and Auger heating. However, little is known (if anything) about the cooling processes in which the spin-degenerate parabolic band splits into two spin-polarized bands, i.e., the Rashba band splitting effect. Here, we investigated the hot-carrier cooling processes for two slightly different compositions of two-dimensional Dion–Jacobson hybrid perovskites, namely, (3AMP)PbI4 and (4AMP)PbI4 (3AMP = 3-(aminomethyl)piperidinium; 4AMP = 4-(aminomethyl)piperidinium), using a combination of ultrafast transient absorption spectroscopy and first-principles calculations. In (4AMP)PbI4, upon Rashba band splitting, the spin-dependent scattering of hot electrons is responsible for accelerating hot-carrier cooling at longer delays. Importantly, the hot-carrier cooling of (4AMP)PbI4 can be extended by manipulating the spin state of the hot carriers. Our findings suggest a new approach for prolonging hot-carrier cooling in hybrid perovskites, which is conducive to further improving the performance of hot-carrier-based optoelectronic and spintronic devices.

scholarly journals Layer- and gate-tunable spin-orbit coupling in a high-mobility few-layer semiconductor

2021 ◽  
Vol 7 (5) ◽  
pp. eabe2892
Author(s):  
Dmitry Shcherbakov ◽  
Petr Stepanov ◽  
Shahriar Memaran ◽  
Yaxian Wang ◽  
Yan Xin ◽  
...  
Keyword(s):  
Electric Field ◽  
High Mobility ◽  
Orbit Coupling ◽  
Spin Splitting ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Quantum Oscillations ◽  
Out Of Plane ◽  
Order Of Magnitude ◽  
Spin Degeneracy

Spin-orbit coupling (SOC) is a relativistic effect, where an electron moving in an electric field experiences an effective magnetic field in its rest frame. In crystals without inversion symmetry, it lifts the spin degeneracy and leads to many magnetic, spintronic, and topological phenomena and applications. In bulk materials, SOC strength is a constant. Here, we demonstrate SOC and intrinsic spin splitting in atomically thin InSe, which can be modified over a broad range. From quantum oscillations, we establish that the SOC parameter α is thickness dependent; it can be continuously modulated by an out-of-plane electric field, achieving intrinsic spin splitting tunable between 0 and 20 meV. Unexpectedly, α could be enhanced by an order of magnitude in some devices, suggesting that SOC can be further manipulated. Our work highlights the extraordinary tunability of SOC in 2D materials, which can be harnessed for in operando spintronic and topological devices and applications.

scholarly journals Microscopic Origin of the Valley Hall Effect in Transition Metal Dichalcogenides Revealed by Wavelength-Dependent Mapping

Nano Letters ◽  
2017 ◽  
Vol 17 (9) ◽  
pp. 5719-5725 ◽  
Author(s):  
Nicolas Ubrig ◽  
Sanghyun Jo ◽  
Marc Philippi ◽  
Davide Costanzo ◽  
Helmuth Berger ◽  
...  
Keyword(s):  
Transition Metal ◽  
Hall Effect ◽  
Transition Metal Dichalcogenides ◽  
Metal Dichalcogenides ◽  
Valley Hall Effect ◽  
Microscopic Origin

scholarly journals Photonic spin Hall effect of monolayer black phosphorus in the Terahertz region

Nanophotonics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 1929-1937 ◽  
Author(s):  
Hai Lin ◽  
Binguo Chen ◽  
Songqing Yang ◽  
Wenguo Zhu ◽  
Jianhui Yu ◽  
...  
Keyword(s):  
Hall Effect ◽  
Black Phosphorus ◽  
Spin Hall Effect ◽  
Spin Splitting ◽  
2D Material ◽  
Terahertz Region ◽  
Incident Plane ◽  
Plane Anisotropy ◽  
High Carrier Mobility ◽  
Light Matter Interaction

AbstractAs a two-dimensional (2D) material, black phosphorus (BP) has attracted significant attention owing to exotic physical properties such as low-energy band gap, high carrier mobility, and strong in-plane anisotropy. The striking in-plane anisotropy is a promising candidate for novel light-matter interaction. Here, we investigate the photonic spin Hall effect (PSHE) on a monolayer of BP. Due to the in-plane anisotropic property of BP, the PSHE is accompanied with Goos-Hänchen and Imbert-Fedorov effects, resulting in an asymmetric spin splitting. The asymmetric spin splitting can be flexibly tuned by the angle between the incident plane and the armchair crystalline direction of BP and by the carrier density via a bias voltage. The centroid displacements of two opposite spin components of the reflected beam along directions parallel and perpendicular to the incident plane can be considered as four independent channels for information processing. The potential application in barcode-encryption is proposed and discussed. These findings provide a deeper insight into the spin-orbit interaction in 2D material and thereby facilitate the development of optoelectronic devices in the Terahertz region.

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