Intrinsic electron spin relaxation due to the D'yakonov–Perel' mechanism in monolayer MoS2

One of the main characteristics of the new family of two-dimensional crystals of semiconducting transition metal dichalcogenides (TMD) is the strong spin-orbit interaction, which makes them very promising for future applications in spintronics and valleytronics devices. Here we present a detailed study of the e ect of spinorbit coupling (SOC) on the band structure of single-layer and bulk TMDs, including explicitly the role of the chalcogen orbitals and their hybridization with the transition metal atoms. To this aim, we combine density functional theory (DFT) calculations with a Slater-Koster tight-binding model. Whereas most of the previous tight-binding models have been restricted to the K and K' points of the Brillouin zone (BZ), here we consider the e ect of SOC in the whole BZ, and the results are compared to the band structure obtained by DFT methods. The tight-binding model is used to analyze the e ect of SOC in the band structure, considering separately the contributions from the transition metal and the chalcogen atoms. Finally, we present a scenario where, in the case of strong SOC, the spin/orbital/valley entanglement at the minimum of the conduction band at Q can be probed and be of experimental interest in the most common cases of electron-doping reported for this family of compounds.

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“…5,8,[28][29][30][31][32] Such scenario can be now well reproduced by the present TB model and generalized to the whole BZ.…”

Section: A Spin-polarized Pockets In the Fermi Surfacessupporting

confidence: 70%

Momentum dependence of spin–orbit interaction effects in single-layer and multi-layer transition metal dichalcogenides

et al. 2014

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“…Therefore, we have to attribute these variations from flake to flake to different concentrations of crystal defects and ionized impurities, which influence momentum scattering rates. While the mechanisms for valley depolarization are currently under intense discussion [51][52][53][54] , momentum scattering at defects is a possible valley dephasing channel. In the aBL region of sample A2, we do not observe any apparent reduction of the valley polarization compared to the MLs, as indicated in the false color map in Figure 8(c).…”

Section: Photoluminescence Spectroscopymentioning

confidence: 99%

Optical spectroscopy of interlayer coupling in artificially stacked MoS ₂ layers

et al. 2015

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We perform an optical spectroscopy study to investigate the properties of different artificial MoS2 bi-and trilayer stacks created from individual monolayers by a deterministic transfer process. These twisted bi-and trilayers differ from the common 2H stacking in mineral MoS2 in the relative stacking angle of adjacent layers and the interlayer distance. The combination of Raman spectroscopy, second-harmonic-generation microscopy and photoluminescence measurements allows us to determine the degree of interlayer coupling in our samples. We find that even for electronically decoupled artificial structures, which show the same valley polarization degree as the constituent MoS2 monolayers at low temperatures, there is a resonant energy transfer between individual layers which acts as an effective luminescence quenching mechanism.

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“…5 For the DP mechanism, in the intrinsic situation, the out-of-plane spin relaxation processes are forbidden due the good quantum number of σ z but the in-plane processes exist, 4,5 including the intravalley and intervalley processes. Particularly, the intervalley process arises from the intrinsic spin-orbit coupling (SOC), which acts as opposite effective magnetic fields in the two valleys and hence opens an intervalley in-plane spin relaxation channel in the presence of the intervalley carrier-phonon scatterings.…”

Section: Introductionmentioning

confidence: 99%

Hole spin relaxation in bilayerWSe2

Yang

Wang

2015

Phys. Rev. B

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We investigate the hole spin relaxation due to the Rashba spin-orbit coupling induced by an external perpendicular electric field in bilayer WSe2. The Rashba spin-orbit coupling coefficients in bilayer WSe2 are constructed from the corresponding monolayer ones. In contrast to monolayer WSe2, the out-of-plane component of the bilayer Rashba spin-orbit coupling acts as a Zeemanlike field with opposite directions but identical values in the two valleys. For in-plane spins, this Zeeman-like field, together with the intervalley hole-phonon scattering, opens an intervalley spin relaxation channel, which is found to dominate the in-plane spin relaxation in bilayer WSe2 even at low temperature. For out-of-plane spins, this Zeeman-like field is superimposed by the identical Hartree-Fock effective magnetic fields in the two valleys, and hence different total effective magnetic fields between two valleys are obtained. Owing to the large difference of the total fields at large spin polarization, different out-of-plane spin relaxation times in the two valleys are obtained when the intervalley hole-phonon scattering is weak at low temperature and low hole density. This difference in the spin relaxation times can be suppressed by enhancing the intervalley hole-phonon scattering through increasing temperature or hole density. Moreover, at large spin polarization and low temperature, due to the weak intravalley hole-phonon scattering but relatively strong hole-hole Coulomb scattering, the fast spin precessions are found to result in a quasi hot-hole Fermi distribution characterized by an effective hot-hole temperature larger than the temperature, which also enhances the intervalley scattering. During this process, it is interesting to discover that the initially equal hole densities in the two valleys are broken in the temporal evolution, and a valley polarization is built up. It is further revealed that this comes from the different spin relaxation processes at large spin polarization and different spin-conserving intervalley scattering rates between spin-up and -down holes due to the different effective hot-hole temperatures.

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Intrinsic electron spin relaxation due to the D'yakonov–Perel' mechanism in monolayer MoS2

Cited by 36 publications

References 63 publications

Momentum dependence of spin–orbit interaction effects in single-layer and multi-layer transition metal dichalcogenides

Momentum dependence of spin–orbit interaction effects in single-layer and multi-layer transition metal dichalcogenides

Optical spectroscopy of interlayer coupling in artificially stacked MoS ₂ layers

Hole spin relaxation in bilayerWSe2

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Intrinsic electron spin relaxation due to the D'yakonov–Perel' mechanism in monolayer MoS2

Cited by 36 publications

References 63 publications

Momentum dependence of spin–orbit interaction effects in single-layer and multi-layer transition metal dichalcogenides

Momentum dependence of spin–orbit interaction effects in single-layer and multi-layer transition metal dichalcogenides

Optical spectroscopy of interlayer coupling in artificially stacked MoS 2 layers

Hole spin relaxation in bilayerWSe2

Contact Info

Product

Resources

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Optical spectroscopy of interlayer coupling in artificially stacked MoS ₂ layers