Fermi velocity engineering in graphene by substrate modification

Hwang, Choongyu; Siegel, David A.; Mo, S.-K.; Regan, William; Ismach, Ariel; Zhang, Yuegang; Zettl, A.; Lanzara, Alessandra

doi:10.1038/srep00590

Cited by 388 publications

(372 citation statements)

References 33 publications

(81 reference statements)

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“…3(d) is for the graphene π states around the K point of the graphene-derived BZ. Analysis of the graphene dispersion relation shows that graphene on BiAg 2 is n doped with a position of the Dirac point of E D = −400 ± 30 meV and a Fermi velocity of (1.17 ± 0.06)×10 6 m/s, which is in good agreement with a value for nearly free-standing graphene on a metallic substrate [34,35].…”

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confidence: 73%

Local electronic properties of the graphene-protected giant Rashba-split BiAg2 surface

et al. 2017

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We report the preparation of an interface between graphene and a strong Rashba-split BiAg 2 surface alloy and an investigation of its structure as well as the electronic properties by means of scanning tunneling microscopy/spectroscopy and density functional theory calculations. Upon evaluation of the quasiparticle interference patterns, an unperturbed linear dispersion for the π band of n-doped graphene is observed. Our results also reveal the intact nature of the giant Rashba-split surface states of the BiAg 2 alloy, which demonstrate only a moderate downward energy shift due to the presence of graphene. This effect is explained in the framework of density functional theory by an inward relaxation of the Bi atoms at the interface and subsequent delocalization of the wave function of the surface states. Our findings demonstrate a realistic pathway to prepare a graphene-protected giant Rashba-split BiAg 2 for possible spintronic applications. DOI: 10.1103/PhysRevB.95.155428 Graphene has attracted much attention due to its unique transport, electronic, and elastic properties [1][2][3]. Taking into account these characteristics, many practical applications of graphene have been proposed. The most promising are graphene-based touch screens, which will potentially replace indium-tin-oxide (ITO-) based screens in the future [4,5], batteries and supercapacitors [6][7][8], and composite materials [9,10]. Above that, a single atom thick graphene layer can effectively protect the underlying material against oxidation and/or corrosion [11,12]. This property is particularly exciting when graphene is deposited or formed on the surface of a ferromagnet or a material which exhibits strong spin-orbit interaction [13][14][15][16][17][18][19]. Here, interfacial contact between graphene and the respective material might lead to the appearance of different new phenomena in graphene and at the interface, such as induced magnetism in graphene [20][21][22], possible induced spin-orbit splitting of the graphene π states [23,24], conservation of spin-polarized electron emission from the underlying ferromagnetic material [13,15], etc.Previously published works on the adsorption of graphene on the surfaces of heavy materials, such as Ir (111) and Au(111), demonstrate that such contacts only weakly modify the dispersion of the spin-orbit split surface states of the metal surface. Adsorption of graphene merely leads to a rigid shift of the respective surface states to smaller binding energies [16,25,26], which was explained by the stronger localization of the surface state wave function, leading to a corresponding energy shift. At the same time, the intercalation of Au in the graphene/Ni(111) interface leads to the appearance of induced spin-orbit splitting of the graphene π states (up to ≈100 meV) as a result of the hybridization of these states and valence band states of the underlying heavy metal [23,24]. Here, the energetically unfavorable model of diluted Au atoms underneath graphene on Ni (111) Here, we report the fabrication of ...

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confidence: 73%

Local electronic properties of the graphene-protected giant Rashba-split BiAg2 surface

et al. 2017

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“…4d). Typically when dielectric screening increases, the electron-electron interactions in graphene are strongly suppressed, so that the graphene band approaches towards the LDA band 33 . Indeed, the band structure of graphene/Cu is in good agreement with the LDA band as compared in Fig.…”

Section: #"mentioning

confidence: 99%

“…The difference between the measured band and the LDA band is a good approximation of the real part of electron self-energy 32,33 . A logarithmic fit to the self-energy that is typically valid for charge neutral graphene 32,33 gives an effective dielectric constant ε = 28.9. Within the standard approximation of ε = (ε vacuum + ε substrate )/2, we obtain ε substrate = 56.8 for the Pt substrate.…”

Section: #"mentioning

confidence: 99%

“…Especially, due to the dimensionality, a two-dimensional system is very sensitive to any interfacial effect and hence easy to engineer its properties. For example, in graphene, not only the basic electronic properties such as charge carrier density 17-20,30-34 , mobility 39 , etc., but also the complicated electronic correlation can be modified by the formation of an interface with various substrates 32,33 . Moreover, intriguing magnetic properties emerges such as a single spin Dirac cone 4 , half-metallicity 11 , spin-dependence variable range hopping 40 , etc., that are not observed when graphene stands alone.…”

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confidence: 99%

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Hole doping, hybridization gaps, and electronic correlation in graphene on a platinum substrate

Hwang

Kim

et al. 2017

Nanoscale

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The interaction between graphene and substrates provides a viable routes to enhance functionality of both materials. Depending on the nature of electronic interaction at the interface, the electron band structure of graphene is strongly influenced, allowing us to make use the intrinsic properties of graphene or to design additional functionality in graphene. Here, we present an angle-resolved photoemission study on the interaction between graphene and a platinum substrate. The formation of an interface between graphene and platinum leads to a strong deviation in the electronic structure of graphene not only from its freestanding form but also from the behavior observed on typical metals. The combined study on the experimental and theoretical electron band structure unveils the unique electronic properties of graphene on a platinum substrate, which singles out graphene/platinum as a model system investigating graphene on a metallic substrate with strong interaction.

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“…In TI devices that are free of magnetic impurities, surface electron backscattering is therefore unlikely. Then, the surface conductance is expected to be limited by the Fermi velocity [7]. Experimental values of the Fermi velocity of Bi2Te3 surfaces show more than 25% variation [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

In-surface confinement of topological insulator nanowire surface states

Chen

Jauregui

Tan

et al. 2015

Applied Physics Letters

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The bandstructures of [110] and [001] Bi2Te3 nanowires are solved with the atomistic 20 band tight binding functionality of NEMO5. The theoretical results reveal: The popular assumption that all topological insulator wire surfaces are equivalent is inappropriate. The Fermi velocity of chemically distinct wire surfaces differs significantly which creates an effective in-surface confinement potential. As a result, topological insulator surface states prefer specific surfaces. Therefore, experiments have to be designed carefully not to probe surfaces unfavorable to the surface states (low density of states) and thereby be insensitive to the TI-effects.

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Fermi velocity engineering in graphene by substrate modification

Cited by 388 publications

References 33 publications

Local electronic properties of the graphene-protected giant Rashba-split BiAg2 surface

Local electronic properties of the graphene-protected giant Rashba-split BiAg2 surface

Hole doping, hybridization gaps, and electronic correlation in graphene on a platinum substrate

In-surface confinement of topological insulator nanowire surface states

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