scholarly journals Dopant Introduced Valley Polarization, Spin, and Valley Hall Conductivity in Doped Monolayer MoS2

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Sintayehu Mekonnen ◽  
Pooran Singh
Keyword(s):  
Hall Conductivity ◽  
Time Inversion ◽  
Spin Orbit Coupling ◽  
Effective Hamiltonian ◽  
Exchange Field ◽  
Monolayer Mos2 ◽  
Magnetic Exchange ◽  
Valley Polarization ◽  
Low Power Electronics ◽  
Spin Hall Conductivity

We study valley polarization, spin, and valley Hall conductivity in doped monolayer MoS2 considering dopant introduced magnetic exchange field using low energy effective Hamiltonian. We found that dopant introduced magnetic exchange field breaks the time inversion symmetry and decouples the energetically degenerated valleys into nondegenerate. Moreover, the calculated result reveals that, at low temperature, in insulating regime, anomalous Hall conductivity in a single valley and the total valley Hall conductivity are quantized, whereas the total spin Hall conductivity vanishes identically. We also found that the strength of the spin-orbit coupling together with the exchange field determines the valley polarization, which in turn controls valley and spin Hall conductivity in doped monolayer MoS2 system. The spin Hall and valley Hall conductivity is dissipationless in the absence of any external magnetic field. Therefore, our results are crucial to generate low power electronics devices.

scholarly journals Relation between the spin Hall conductivity and the spin Chern number for Dirac-like systems

2016 ◽  
Vol 13 (01) ◽  
pp. 1550136 ◽  
Author(s):  
Ömer F. Dayi ◽  
Elif Yunt
Keyword(s):  
Hall Effect ◽  
Chern Number ◽  
Hall Conductivity ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Quantum Level ◽  
Coupling Term ◽  
Physical Systems ◽  
Rashba Spin ◽  
Spin Hall Conductivity

A semiclassical formulation of the spin Hall effect for physical systems satisfying Dirac-like equation is introduced. We demonstrate that the main contribution to the spin Hall conductivity is given by the spin Chern number whether the spin is conserved or not at the quantum level. We illustrated the formulation within the Kane–Mele model of graphene in the absence and in the presence of the Rashba spin-orbit coupling term.

scholarly journals Prediction of crossing nodal-lines and large intrinsic spin Hall conductivity in topological Dirac semimetal Ta3As family

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wenjie Hou ◽  
Jian Liu ◽  
Xi Zuo ◽  
Jian Xu ◽  
Xueying Zhang ◽  
...  
Keyword(s):  
Fermi Level ◽  
Hall Conductivity ◽  
Spin Orbit Coupling ◽  
First Principles Calculations ◽  
Practical Applications ◽  
Nodal Lines ◽  
Dirac Semimetal ◽  
Topological Semimetals ◽  
The Ideal ◽  
Spin Hall Conductivity

AbstractTopological insulators (TIs) are considered as ideal platforms for generating large spin Hall conductivity (SHC), however, the bulk carrier problem, which is unavoidable in TIs, hinders their practical applications. Recently, topological semimetals (TSMs) have been proposed to achieve large SHC to replace TIs. However, the ideal TSM candidates with large SHC are still lacking. In terms of first-principles calculations, we predict that Ta3As family compounds exhibit complex crossing nodal-lines (CNL) properties in absence of the spin-orbit coupling (SOC). However, they transfer to Dirac TSMs under the influence of strong SOC, and present large SHC around Fermi level in particular. Remarkably, the SHC value of Ta3Y (Y = As, Sb, Bi) is around 1500–1700 $$(\hbar /e)({\mathrm{{\Omega}}} \cdot {\mathrm{cm}})^{ - 1}$$ ( ħ / e ) ( Ω ⋅ cm ) − 1 , which is comparable to noble metal Pt and much larger than TIs, Weyl TSMs, and 4d/5d transition metals. Our work not only suggests a kind of TSM family with interesting Dirac CNL around Fermi level, but also paves the way for searching large intrinsic SHC materials in complex CNL TSM systems.

scholarly journals Kubo–Bastin approach for the spin Hall conductivity of decorated graphene

2D Materials ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. 024007 ◽  
Author(s):  
Jose H Garcia ◽  
Tatiana G Rappoport
Keyword(s):  
Hall Conductivity ◽  
Spin Hall Conductivity

Photo- and exchange-field controlled line-type resonant peaks and enhanced spin and valley polarizations in a magnetic WSe2 junction

2022 ◽  
Author(s):  
Mohammad Alipour zadeh ◽  
Yaser Hajati ◽  
Imam Makhfudz
Keyword(s):  
Transport Properties ◽  
Resonant Tunneling ◽  
High Efficiency ◽  
Oscillatory Behavior ◽  
Spin Orbit Coupling ◽  
Exchange Field ◽  
Ideal Line ◽  
Transmission Resonances ◽  
Filtering Effect ◽  
Line Type

Abstract Existing resonant tunneling modes in the shape of line-type resonances can improve the transport properties of the junction. Motivated by the unique structural properties of monolayer WSe2 e.g. significant spin-orbit coupling (SOC) and large direct bandgap, the transport properties of a normal/ferromagnetic/normal (NFN) WSe2 junction with large incident angles in the presence of exchange field (h), off-resonance light (∆Ω) and gate voltage (U) is studied. In a certain interval of U, the transmission shows a gap with optically controllable width, while outside it, the spin and valley resolved transmissions have an oscillatory behavior with respect to U. By applying ∆Ω (h), an optically (electrically) switchable perfect spin and valley polarizations at all angles of incidence have been found. For large incident angles, the transmission resonances change to spin-valley-dependent separated ideal line-type resonant peaks with respect to U, resulting in switchable perfect spin and valley polarizations, simultaneously. Furthermore, even in the absence of U, applying h or ∆Ω at large incident angles can give some spin-valley dependent ideal transmission peaks, making h or ∆Ω a transmission valve capable of giving a switchable fully spinvalley filtering effect. These findings suggest some alternate methods for providing high-efficiency spin and valley filtering devices based on WSe2.

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