Extrinsic spin Hall effect from anisotropic Rashba spin-orbit coupling in graphene

Yang, Hung‐Yu; Huang, Chunli; Ochoa, Héctor; Cazalilla, Miguel A.

doi:10.1103/physrevb.93.085418

Cited by 31 publications

(38 citation statements)

References 32 publications

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“…These reports follow prior work on weakly hydrogenated graphene, which surprisingly showed similar results [13]. These large values of θ sH have been supported by semiclassical transport analysis [14,15].…”

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confidence: 87%

Spin Hall Effect and Origins of Nonlocal Resistance in Adatom-Decorated Graphene

et al. 2016

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Recent experiments on the spin Hall effect (SHE) in graphene with adatoms, reporting unexpectedly large charge-to-spin conversion efficiency, have raised a fierce controversy. Here, we apply numerically exact Kubo and Landauer-Büttiker formulas to realistic disordered models of golddecorated graphene (including adatom segregation) to compute the spin Hall conductivity and spin Hall angle, as well as the nonlocal resistance which is directly measured in experiments. Large spin Hall angles of ≃ 0.1 are obtained at zero-temperature, but their dependence on adatom segregation differ from the predictions of semiclassical transport theories. Furthermore, our findings evidence multiple contributions to the nonlocal resistance, some unrelated to the SHE, and a strong suppression of the SHE at room temperature, which altogether cast doubts on recent claims of giant SHE in graphene. All this calls for future experiments to unambiguously reveal the existence of SHE physics and clarify the upper limit on spin current generation by two-dimensional materials.

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confidence: 87%

Spin Hall Effect and Origins of Nonlocal Resistance in Adatom-Decorated Graphene

et al. 2016

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“…The important role played by the SOC symmetry in the resonant scattering regime has been elucidated by recent theoretical studies [17,23]. The suitability of graphene for all-electrical spintronics is further supported by recent experimental reports on nonlocal transport in adatom-decorated graphene in Refs.…”

Section: Introductionmentioning

confidence: 81%

Quantum diagrammatic theory of the extrinsic spin Hall effect in graphene

Milletarì

Ferreira

2016

Phys. Rev. B

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We present a rigorous microscopic theory of the extrinsic spin Hall effect in disordered graphene based on a nonperturbative quantum diagrammatic treatment incorporating skew scattering and anomalous (impurityconcentration-independent) quantum corrections on equal footing. The leading skew-scattering contribution to the spin Hall conductivity is shown to quantitatively agree with Boltzmann transport theory over a wide range of parameters. Our self-consistent approach, where all topologically equivalent noncrossing diagrams are resummed, unveils that the skewness generated by spin-orbit-active impurities deeply influences the anomalous component of the spin Hall conductivity, even in the weak-scattering regime. This seemingly counterintuitive result is explained by the rich sublattice structure of scattering potentials in graphene, for which traditional Gaussian disorder approximations fail to capture the intricate correlations between skew scattering and side jumps generated through diffusion. Finally, we assess the role of quantum interference corrections by evaluating an important subclass of crossing diagrams recently considered in the context of the anomalous Hall effect, the X and diagrams [A. Ado et al., Europhys. Lett. 111, 37004 (2015)]. We show that diagrams, encoding quantum coherent skew scattering, display a strong Fermi energy dependence, dominating the anomalous spin Hall component away from the Dirac point. Our findings have direct implications for nonlocal transport experiments in spin-orbit-coupled graphene systems.

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“…Eq. (2) shows that there are two distinct mechanisms contributing to the CISP: (i) the extrinsic Edelstein effect which is a two-step process associated with θ sH α R , and (ii) the ASP scattering which is associated with α asp . The first term is formally identical to the Edelstein effect found in the 2D electron gas, 43 with one important difference: the effect here is of extrinsic origin.…”

Section: A Current-induced Spin Polarizationmentioning

confidence: 99%

Direct coupling between charge current and spin polarization by extrinsic mechanisms in graphene

2016

Self Cite

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Spintronics-the all-electrical control of the electron spin for quantum or classical information storage and processing-is one of the most promising applications of the two-dimensional material graphene. Although pristine graphene has negligible spin-orbit coupling (SOC), both theory and experiment suggest that SOC in graphene can be enhanced by extrinsic means, such as functionalization by adatom impurities. We present a theory of transport in graphene that accounts for the spin-coherent dynamics of the carriers, including hitherto-neglected spin precession processes taking place during resonant scattering in the dilute impurity limit. We uncover a novel "anisotropic spin precession" (ASP) scattering process in graphene, which contributes a large current-induced spin polarization and modifies the standard spin Hall effect. ASP scattering arises from two dimensionality and extrinsic SOC, and apart from graphene, it can be present in other 2D materials or in the surface states of 3D materials with a fluctuating SOC. Our theory also yields a comprehensive description of the spin relaxation mechanisms present in adatom-decorated graphene, including Elliot-Yafet and D'yakonov-Perel relaxation rates, the latter of which can become an amplification process in a certain parameter regime of the SOC disorder potential. Our work provides theoretical foundations for designing future graphene-based integrated spintronic devices.

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Extrinsic spin Hall effect from anisotropic Rashba spin-orbit coupling in graphene

Cited by 31 publications

References 32 publications

Spin Hall Effect and Origins of Nonlocal Resistance in Adatom-Decorated Graphene

Spin Hall Effect and Origins of Nonlocal Resistance in Adatom-Decorated Graphene

Quantum diagrammatic theory of the extrinsic spin Hall effect in graphene

Direct coupling between charge current and spin polarization by extrinsic mechanisms in graphene

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