Are Al2O3 and MgO tunnel barriers suitable for spin injection in graphene?

Dlubak, Bruno; Sénéor, Pierre; Anane, A.; Barraud, Clément; Deranlot, C.; Deneuve, D.; Servet, Bernard; Mattana, R.; Pétroff, F.; Fert, A.

doi:10.1063/1.3476339

Cited by 87 publications

(91 citation statements)

References 28 publications

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“…Oxide tunnel barriers are known to be very difficult to form on graphene since they exhibit de-wetting in the absence of prior chemical treatment of the graphene, and attempts to mitigate this to create a good surface for oxide growth may induce scatterers and defects 34 . Thick oxide tunnel barriers can also irreversibly structurally damage graphene 35 . In all of these cases, it would be difficult to measure the intrinsic properties of the graphene itself.…”

Section: Discussionmentioning

confidence: 99%

Homoepitaxial tunnel barriers with functionalized graphene-on-graphene for charge and spin transport

Friedman

Erve

et al. 2014

Nat Commun

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The coupled imperatives for reduced heat dissipation and power consumption in high-density electronics have rekindled interest in devices based on tunnelling. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, layer uniformity, interface stability and electronic states that severely complicate fabrication and compromise performance. Twodimensional materials such as graphene obviate these issues and offer a new paradigm for tunnel barriers. Here we demonstrate a homoepitaxial tunnel barrier structure in which graphene serves as both the tunnel barrier and the high-mobility transport channel. We fluorinate the top layer of a graphene bilayer to decouple it from the bottom layer, so that it serves as a single-monolayer tunnel barrier for both charge and spin injection into the lower graphene channel. We demonstrate high spin injection efficiency with a tunnelling spin polarization 460%, lateral transport of spin currents in non-local spin-valve structures and determine spin lifetimes with the Hanle effect.

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Section: Discussionmentioning

confidence: 99%

Homoepitaxial tunnel barriers with functionalized graphene-on-graphene for charge and spin transport

Friedman

Erve

et al. 2014

Nat Commun

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“…To prevent this mismatch, high resistive barriers between the contacts and the graphene channel are included. 4,[19][20][21][22][23] The most common and reliable way to probe spin transport properties is by performing measurements in the nonlocal spin valve geometry 2,5,24 because it enables the separation of spin and charge currents, avoiding spurious effects. 25 Popinciuc et al 19 describe, in agreement with Takahashi and Maekawa,26 that the measured amplitude of the spin signal in the nonlocal geometry is strongly reduced for low contact resistances R C .…”

Section: Introductionmentioning

confidence: 99%

Contact-induced spin relaxation in Hanle spin precession measurements

et al. 2012

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. In the field of spintronics the "conductivity mismatch" problem remains an important issue. Here the difference between the resistance of ferromagnetic electrodes and a (high resistive) transport channel causes injected spins to be backscattered into the leads and to lose their spin information. We study the effect of the resulting contact-induced spin relaxation on spin transport, in particular on nonlocal Hanle precession measurements. As the Hanle line shape is modified by the contact-induced effects, the fits to Hanle curves can result in incorrectly determined spin transport properties of the transport channel. We quantify this effect that mimics a decrease of the spin relaxation time of the channel reaching more than four orders of magnitude and a minor increase of the diffusion coefficient by less than a factor of two. Then we compare the results to spin transport measurements on graphene from the literature. We further point out guidelines for a Hanle precession fitting procedure that allows the reliable extraction of spin transport properties from measurements.

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“…Most studies use oxides for a tunnel barrier, which contain defects and pinholes, non-uniformities, and offer severe difficulties in wetting the surface of the graphene consistently. 9,10 Promising new candidates to replace oxides for tunnel barriers on graphene include other 2D materials such as BN 11 or amorphous carbon films. 12 Perhaps the most promising candidate is a homoepitaxial tunnel barrier made from graphene itself, 13,14 lightly functionalized with either fluorine or hydrogen.…”

Section: Introductionmentioning

confidence: 99%

Homoepitaxial graphene tunnel barriers for spin transport

et al. 2016

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Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

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Are Al2O3 and MgO tunnel barriers suitable for spin injection in graphene?

Cited by 87 publications

References 28 publications

Homoepitaxial tunnel barriers with functionalized graphene-on-graphene for charge and spin transport

Homoepitaxial tunnel barriers with functionalized graphene-on-graphene for charge and spin transport

Contact-induced spin relaxation in Hanle spin precession measurements

Homoepitaxial graphene tunnel barriers for spin transport

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