Measuring anisotropic spin relaxation in graphene

Ringer, Sebastian; Hartl, Stefan; Rosenauer, Matthias; Völkl, Tobias; Kadur, Maximilian; Hopperdietzel, Franz; Weiss, Dieter; Eroms, Jonathan

doi:10.1103/physrevb.97.205439

Cited by 33 publications

(28 citation statements)

References 40 publications

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“…It has to be noted that fabricating spin selective contacts in graphene that was hydrogenated by this method proved to be difficult in general. Further, the extracted spin lifetime of τ s = 146 ps is much smaller than what was observed in pristine graphene with tunneling contacts produced by the same method 19 .This is in contrast to the findings of Wojtaszek et al who observed an increase in spin lifetime after treating pristine graphene with hydrogen plasma 20 . This small value for the spin lifetime can be caused by either an increased contact-induced spin relaxation due to an increase in the number of pinholes 21 or due to increased spin relaxation by the presence of hydrogen atoms acting as magnetic impurities 22 .…”

Section: Inverse Spin Hall Effect In Hydrogenated Graphenecontrasting

confidence: 59%

Absence of a giant spin Hall effect in plasma-hydrogenated graphene

et al. 2019

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The weak spin-orbit interaction in graphene was predicted to be increased, e.g., by hydrogenation. This should result in a sizable spin Hall effect (SHE). We employ two different methods to examine the spin Hall effect in weakly hydrogenated graphene. For hydrogenation we expose graphene to a hydrogen plasma and use Raman spectroscopy to characterize this method. We then investigate the SHE of hydrogenated graphene in the H-bar method and by direct measurements of the inverse SHE. Although a large nonlocal resistance can be observed in the H-bar structure, comparison with the results of the other method indicate that this nonlocal resistance is caused by a non-spin-related origin.arXiv:1809.10475v1 [cond-mat.mes-hall]

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Section: Inverse Spin Hall Effect In Hydrogenated Graphenecontrasting

confidence: 59%

Absence of a giant spin Hall effect in plasma-hydrogenated graphene

et al. 2019

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“…Here we study τ ⊥ and τ in fully hBN encapsulated BLG using oblique spin precession. Our results show that, in contrast with monolayer graphene [17,[19][20][21], at temperatures below 300 K, the ratio τ ⊥ /τ is significantly above 1 over the full measured range of n. At 75 K we observe a dependence of τ ⊥ /τ on the carrier concentration which increases from 3.5 ± 1 at n = 6 × 10 11 cm −2 to 8 ± 2 at the CNP confirming the role of the spinvalley coupling on the spin transport. The anisotropy at the CNP is comparable to graphene/TMD systems [6,7].…”

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confidence: 83%

Observation of Spin-Valley-Coupling-Induced Large Spin-Lifetime Anisotropy in Bilayer Graphene

et al. 2018

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We report the first observation of a large spin lifetime anisotropy in bilayer graphene (BLG) fully encapsulated between hexagonal boron nitride. We characterize the out-of-plane (τ ⊥ ) and in-plane (τ ) spin lifetimes by oblique Hanle spin precession. At 75 K and the charge neutrality point (CNP) we observe a strong anisotropy of τ ⊥ /τ = 8 ± 2. This value is comparable to graphene/TMD heterostructures, whereas our high quality BLG provides with τ ⊥ up to 9 ns, a more than two orders of magnitude larger spin lifetime. The anisotropy decreases to 3.5 ± 1 at a carrier density of n = 6 × 10 11 cm −2 . Temperature dependent measurements show above 75 K a decrease of τ ⊥ /τ with increasing temperature, reaching the isotropic case close to room temperature. We explain our findings with electric field induced spin-valley coupling arising from the small intrinsic spin orbit fields in BLG of 12 µeV at the CNP.

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“…Meanwhile, spin relaxation owing to strain-induced gauge fields 60 is predicted to yield ζ > 1. Recent measurements of graphene on SiO 2 substrates 54,109,110,113,129 have revealed ζ ≈ 1. This rules out the DP mechanism, as well as strain and corrugation, as the main drivers of spin relaxation in these measurements and further supports magnetic impurities or spin-pseudospin coupling.…”

Section: History Of Spin Transport In Graphene 21 Graphene On Traditmentioning

confidence: 99%

Spin transport in graphene/transition metal dichalcogenide heterostructures

et al. 2018

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Since its discovery, graphene has been a promising material for spintronics: its low spin-orbit coupling, negligible hyperfine interaction, and high electron mobility are obvious advantages for transporting spin information over long distances. However, such outstanding transport properties also limit the capability to engineer active spintronics, where strong spin-orbit coupling is crucial for creating and manipulating spin currents. To this end, transition metal dichalcogenides, which have larger spin-orbit coupling and good interface matching, appear to be highly complementary materials for enhancing the spin-dependent features of graphene while maintaining its superior charge transport properties. In this review, we present the theoretical framework and the experiments performed to detect and characterize the spin-orbit coupling and spin currents in graphene/transition metal dichalcogenide heterostructures. Specifically, we will concentrate on recent measurements of Hanle precession, weak antilocalization and the spin Hall effect, and provide a comprehensive theoretical description of the interconnection between these phenomena.

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Measuring anisotropic spin relaxation in graphene

Cited by 33 publications

References 40 publications

Absence of a giant spin Hall effect in plasma-hydrogenated graphene

Absence of a giant spin Hall effect in plasma-hydrogenated graphene

Observation of Spin-Valley-Coupling-Induced Large Spin-Lifetime Anisotropy in Bilayer Graphene

Spin transport in graphene/transition metal dichalcogenide heterostructures

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