Electrical control of the valley Hall effect in bilayer MoS2 transistors

Lee, Jieun; Mak, Kin Fai; Shan, Jie

doi:10.1038/nnano.2015.337

Cited by 387 publications

(355 citation statements)

References 39 publications

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“…This is inspired by recent successful applications of the reversible electric approach to manipulate valley-contrasting properties of bilayer graphene, 20,[26][27][28][29][30][31] and the more promising transition-metal dichalcogenides (TMDs) bilayers. 32,33 The realization of the effect hinges on optionally control of valley degeneracy through an electric field. Initially, owing to the antiferrovalley coupling between single layers, band structures between two valley indexes are degenerate, demonstrating an inversion symmetric system with absence of AVHE.…”

Section: Introductionmentioning

confidence: 99%

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Tong

Duan

2017

npj Quant Mater

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In analogy to all-electric spintronics, all-electric valleytronics, i.e., valley manipulation via electric means, becomes an exciting new frontier as it may bring revolutions in the field of data storage with ultra-high speed and ultra-low power consumption. The existence of the anomalous valley Hall effect in ferrovalley materials demonstrates the possibility of electrical detection for valley polarization. However, in previously proposed valley-polarized monolayers, the anomalous valley Hall effect is controlled by external magnetic fields. Here, through elaborate structural design, we propose the antiferrovally bilayer as an ideal candidate for realizing all-electric valleytronic devices. Using the minimal k·p model, we show that the energy degeneracy between valley indexes in such system can be lifted by electric approaches. Subsequently, the anomalous valley Hall effect strongly depends on the electric field as well. Taking the bilayer VSe 2 as an example, all-electric tuning and detecting of anomalous valley Hall effect is confirmed by density-functional theory calculations, indicating that the valley information in such antiferrovalley bilayer can be reversed by an electric field perpendicular to the plane of the system and easily probed through the sign of the Hall voltage.

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Section: Introductionmentioning

confidence: 99%

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Tong

Duan

2017

npj Quant Mater

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“…These properties have also been actively explored for new electronics and optoelectronics applications [4][5][6][7][8][9][10][11][12][13][14][15] . In the monolayer limit, group-VI TMDs (MX 2 , M = Mo, W; X = S, Se) are direct band-gap semiconductors with the fundamental energy gap located at the K and K' points of the Brillouin zone 16,17 .…”

mentioning

confidence: 99%

“…Understanding the spin-polarized conduction band structure is important for a wide array of spin-related phenomena in monolayer TMDs. Examples include the exciton optical selection rules 1,3,20,21 , exciton and spin lifetimes 18,[21][22][23] , and the spin and valley Hall effects 1,12,15 . A large ∆ !…”

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confidence: 99%

Probing the Spin-Polarized Electronic Band Structure in Monolayer Transition Metal Dichalcogenides by Optical Spectroscopy

et al. 2017

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We study the electronic band structure in the K/K' valleys of the Brillouin zone of monolayer WSe 2 and MoSe 2 by optical reflection and photoluminescence spectroscopy on dual-gated field-effect devices. Our experiment reveals the distinct spin polarization in the conduction bands of these compounds by a systematic study of the doping dependence of the A and B excitonic resonances. Electrons in the highest-energy valence band and the lowest-energy conduction band have antiparallel spins in monolayer WSe 2 , and parallel spins in monolayer MoSe 2 . The spin splitting is determined to be hundreds of meV for the valence bands and tens of meV for the conduction bands, which are in good agreement with first principles calculations. These values also suggest that both n-and ptype WSe 2 and MoSe 2 can be relevant for spin-and valley-based applications.

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“…The emerging 2D transition metal dichalcogenides (TMDs), due to their strong spin splitting in d orbits and valley momentum separation,1 provide a fertile ground to explore the spin and valley degrees of freedom 2, 3. The intrinsic inversion symmetry breaking in monolayer hexagonal 2H‐TMDs (MX 2 with M = W, Mo and X = Se, S) generates the valley‐contrasting optical selection rules.…”

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confidence: 99%

Room‐Temperature Nanoseconds Spin Relaxation in WTe₂ and MoTe₂ Thin Films

Wang

Besbas

et al. 2018

Advanced Science

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The Weyl semimetal WTe2 and MoTe2 show great potential in generating large spin currents since they possess topologically protected spin‐polarized states and can carry a very large current density. In addition, the intrinsic non‐centrosymmetry of WTe2 and MoTe2 endows with a unique property of crystal symmetry‐controlled spin–orbit torques. An important question to be answered for developing spintronic devices is how spins relax in WTe2 and MoTe2. Here, a room‐temperature spin relaxation time of 1.2 ns (0.4 ns) in WTe2 (MoTe2) thin film using the time‐resolved Kerr rotation (TRKR) is reported. Based on ab initio calculation, a mechanism of long‐lived spin polarization resulting from a large spin splitting around the bottom of the conduction band, low electron–hole recombination rate, and suppression of backscattering required by time‐reversal and lattice symmetry operation is identified. In addition, it is found that the spin polarization is firmly pinned along the strong internal out‐of‐plane magnetic field induced by large spin splitting. This work provides an insight into the physical origin of long‐lived spin polarization in Weyl semimetals, which could be useful to manipulate spins for a long time at room temperature.

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Electrical control of the valley Hall effect in bilayer MoS2 transistors

Cited by 387 publications

References 39 publications

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Probing the Spin-Polarized Electronic Band Structure in Monolayer Transition Metal Dichalcogenides by Optical Spectroscopy

Room‐Temperature Nanoseconds Spin Relaxation in WTe₂ and MoTe₂ Thin Films

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Electrical control of the valley Hall effect in bilayer MoS2 transistors

Cited by 387 publications

References 39 publications

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Electrical control of the anomalous valley Hall effect in antiferrovalley bilayers

Probing the Spin-Polarized Electronic Band Structure in Monolayer Transition Metal Dichalcogenides by Optical Spectroscopy

Room‐Temperature Nanoseconds Spin Relaxation in WTe2 and MoTe2 Thin Films

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Room‐Temperature Nanoseconds Spin Relaxation in WTe₂ and MoTe₂ Thin Films