Demonstration of surface transport in a hybrid Bi2Se3/Bi2Te3 heterostructure

Zhao, Yijiao; Chang, Cui-Zu; Jiang, Ying; DaSilva, Ashley; Sun, Yi; Wang, Huichao; Xing, Ying; Wang, Yong; He, Ke; Ma, Xu-Cun; Xue, Qi‐Kun; Wang, Jian

doi:10.1038/srep03060

Cited by 72 publications

(58 citation statements)

References 42 publications

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“…For metals, where the ratio τ φ /τ e is very large (of the order of 1000 [27]) this crossover occurs for a value ofλ small enough that a perturbative treatment is possible. However, for the parameters experimentally relevant for 3DTIs, with a smaller ratio τ φ /τ e around 10 [22][23][24], this crossover occurs for values ofλ of the order of the unity, which is beyond the range of validity of the HLN derivation. We have plotted in Fig.…”

Section: Expression For the Cooperon Modes And Their Contribution To Walmentioning

confidence: 94%

Conductivity corrections for topological insulators with spin-orbit impurities: Hikami-Larkin-Nagaoka formula revisited

et al. 2015

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The Hikami-Larkin-Nagaoka (HLN) formula [Prog. Theor. Phys. 63, 707 (1980)] describes the quantum corrections to the magnetoconductivity of a quasi-2D electron gas (quasi-2DEG) with parabolic dispersion. It predicts a crossover from weak localization to antilocalization as a function of the strength of scattering off spin-orbit impurities. Here, we derive the conductivity correction for massless Dirac fermions in 3D topological insulators (3DTIs) in the presence of spin-orbit impurities. We show that this correction is always positive and therefore we predict weak antilocalization for every value of the spin-orbit disorder. Furthermore, the correction to the diffusion constant is surprisingly linear in the strength of the impurity spin-orbit. Our results call for a reinterpretation of experimental fits for the magnetoconductivity of 3D TIs which have so far used the standard HLN formula.PACS numbers: 73.20.Fz, 73.43.Qt, 73.25.+i Introduction. The problem of the diffusion of the surface states of 3DTIs is a complex one due to a variety of competing phenomena. The most striking is the fact that these surface states are described by a Dirac Hamiltonian [1,2], which gives rise to weak antilocalization (WAL) in the presence of scalar disorder [3][4][5]. The WAL correction can be affected by the interaction of the surface states with the residual bulk states [6], the thickness of the film [7], or electron-electron interactions [8,9] changing its sign and turning it into weak localization (WL). At the same time, since 3DTIs have strong spin-orbit coupling, one expects spin-orbit coupled impurities to have a strong effect on transport, different however than in graphene where two valleys are present [10,11]. Surprisingly this problem has received virtually no attention [12] and so far the Dirac nature of the states, that manifest itself in the angular dependence of the Green functions, has not been taken into account in studies of spin-orbit impurities [7]. The problem is even more complicated in a transverse magnetic field.The formula commonly used to fit the magnetoconductance experiments on 3DTIs [13][14][15][16][17][18][19][20] was derived by Hikami, Larkin and Nagaoka (HLN) [21]. The HLN formula, however, lacks important features relevant to 3DTIs: it is derived for quasi-2DEGs with a parabolic electron dispersion (impurities are treated as threedimensional objects), so it accounts neither for the Dirac nature of the surface states nor for their strictly twodimensional character. Fig. 1 is the main result of this paper, and shows the different effects of spin-orbit scatter- * The two first authors contributed equally.† Author to whom correspondence should be addressed : hankiewicz@physik.uni-wuerzburg.de ing for the HLN formula, namely WL to WAL crossover with the strength of spin-orbit impurity scattering, and for Dirac fermions, where WAL appears regardless of the strength of spin-orbit impurities. We only observe a convergence of the two formulas for large values of the strength of the impurity spin-orbit sc...

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Section: Expression For the Cooperon Modes And Their Contribution To Walmentioning

confidence: 94%

Conductivity corrections for topological insulators with spin-orbit impurities: Hikami-Larkin-Nagaoka formula revisited

et al. 2015

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“…4(a), presenting features which could arise from phonons in the AlO x , 33 the TI, 34 or coupled AlO x -TI modes. The occurrence of inelastic tunneling processes with the addition of sequential tunneling observed in shot 28 noise measurements (not shown) could lead to a fraction of the carriers being inelastically back-scattered against the flow of the current. 35 This could explain why the peaks in 1/f noise are observed for both signs of the bias.…”

mentioning

confidence: 99%

Band structure of topological insulators from noise measurements in tunnel junctions

Cascales

Martínez

Katmis

et al. 2015

Applied Physics Letters

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The unique properties of spin-polarized surface or edge states in topological insulators (TIs) make these quantum coherent systems interesting from the point of view of both fundamental physics and their implementation in low power spintronic devices. Here we present such a study in TIs, through tunneling and noise spectroscopy utilizing TI/Al 2 O 3 /Co tunnel junctions with bottom TI electrodes of either Bi 2 Te 3 or Bi 2 Se 3 . We demonstrate that features related to the band structure of the TI materials show up in the tunneling conductance and even more clearly through low frequency noise measurements. The bias dependence of 1/f noise reveals peaks at specific energies corresponding to band structure features of the TI. TI tunnel junctions could thus simplify the study of the properties of such quantum coherent systems that can further lead to the manipulation of their spin-polarized properties for technological purposes. A topological insulator (TI) is a material which is insulating in the bulk but presents spin-dependent conducting edge or surface states which are protected by time-reversal symmetry.1-3 A 2D or 3D TI presents edge or surface states, respectively, which are spin-polarized in-plane, and locked at right angles to the carrier momentum, so that electrons with spin-up/down propagate in opposite directions. The edge or surface states of a TI consist of an odd number of massless Dirac cones. These properties along with their high mobility make TI materials interesting for next generation, low dissipation, and spintronic applications 4,5 in which the electron spins are manipulated even without any magnetic fields. The experimental surge regarding these materials occurred with the prediction of Bi-based TIs 6 and their posterior experimental realization.7 Bi 2 Se 3 and Bi 2 Te 3 , in particular, became the prototypical TI materials that were studied most heavily.To date, the experimental verification of the band structure of TI materials has been predominantly carried out by angle-resolved photoemission spectroscopy (ARPES), which yields energy-momentum graphs of band dispersion for probing depths of under a few nm. 7,8 Also, the use of spin-ARPES has allowed the determination of the spin dependence of the topological surface states. 9 On the other hand, the use of scanning tunneling microscope (STM) allows obtaining information regarding the local density of states (DOS) and the topography of surfaces. By the study of quasiparticle scattering with STM, bands can be mapped very close to the Fermi surface, with a considerably lower energy range and at a smaller scale than with ARPES. [10][11][12][13] Although immensely useful, these techniques are usually cumbersome and the conditions of study are far from a practical application of TIs. A versatile and relatively simple technique to determine the DOS of TI materials could be the study of electronic transport and noise through planar tunneling devices. So far, individual or heterostructure devices with TI layers have mainly dealt with lateral electro...

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“…LMR has been found only in limited materials, including silver chalcogenides [1], multilayer epitaxial graphene [2], topological insulators [3][4][5], three dimensional Dirac semimetal such as Cd 3 As 2 [6][7][8] and TlBiSSe [9], which has often been interpreted by either the theory proposed by Abrikosov [10] or the inhomogeneity in materials [1]. LMR behaviors are usually observed in a magnetic field applied perpendicular to the direction of the excitation current and have become one of the significant research interests in condensed matter physics and material science.…”

mentioning

confidence: 99%

Anisotropic magnetotransport and exotic longitudinal linear magnetoresistance inWTe2crystals

et al. 2015

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WTe 2 semimetal, as a typical layered transition-metal dichalcogenide, has recently attracted much attention due to the extremely large, non-saturating parabolic magnetoresistance in perpendicular field. Here, we report a systematic study of the angular dependence of the magnetoresistance in WTe 2 single crystal. The violation of the Kohler rule and a significant anisotropic magnetotransport behavior in different magnetic field directions are observed. Surprisingly, when the applied field is parallel to the tungsten chains of WTe 2 , an exotic large longitudinal linear magnetoresistance as high as 1200% at 15 T and 2 K is identified. Violation of the Kohler rule in transverse magnetoresistance can be understood based on a dual effect of the excitons formation and thermal activation, while large longitudinal linear magnetoresistance reflects perfectly the scattering and nesting of quasi-1D nature of this balanced hole-electron

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Demonstration of surface transport in a hybrid Bi2Se3/Bi2Te3 heterostructure

Cited by 72 publications

References 42 publications

Conductivity corrections for topological insulators with spin-orbit impurities: Hikami-Larkin-Nagaoka formula revisited

Conductivity corrections for topological insulators with spin-orbit impurities: Hikami-Larkin-Nagaoka formula revisited

Band structure of topological insulators from noise measurements in tunnel junctions

Anisotropic magnetotransport and exotic longitudinal linear magnetoresistance inWTe2crystals

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