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

Johannes Christian Leutenantsmeyer*, Josep Ingla-Aynes, Jaroslav Fabian, Bart J. van Wees

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

25 Citaten (Scopus)
4 Downloads (Pure)

Samenvatting

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 (tau(perpendicular to)) and in-plane (tau(parallel to)) spin lifetimes by oblique Hanle spin precession. At 75 K and the charge neutrality point (CNP), we observe a strong anisotropy of tau(perpendicular to)/tau(parallel to) = 8 +/- 2. This value is comparable to graphene-transition-metal-dichalcogenide heterostructures, whereas our high-quality BLG provides with tau(perpendicular to) up to 9 ns, a spin lifetime more than 2 orders of magnitude larger. The anisotropy decreases to 3.5 +/- 1 at a carrier density of n = 6 x 10(11) cm(-2). Temperature-dependent measurements show above 75 K a decrease of tau(perpendicular to)/tau(parallel to) 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 mu eV at the CNP.

Originele taal-2English
Artikelnummer127702
Aantal pagina's6
TijdschriftPhysical Review Letters
Volume121
Nummer van het tijdschrift12
DOI's
StatusPublished - 20-sep-2018

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