Aharonov-Bohm oscillations and weak antilocalization in topological insulator Sb2Te3 nanowires

Hamdou, Bacel; Gooth, Johannes; Dorn, August; Pippel, Eckhard; Nielsch, Kornelius

doi:10.1063/1.4809826

Cited by 55 publications

(67 citation statements)

References 28 publications

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“…1 10,[41][42][43] Regardless of the gate voltage we observe three pronounced features in the magnetoresistance at 2 K as is exemplarily shown for V G = +10 V in Fig. 1c: first, a smoothly varying background, ascribed to the nanowire bulk; 5,7,9 second, a sharp dip around zero magnetic field, attributed to WAL consistent with strong spin-orbit coupling; 5,[8][9][10]23,24 and third, at higher magnetic fields, superimposed SdH oscillations that reveal a 1/B periodicity.…”

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“…2 b). 20,37,38 For 1/B < 0.7 T -1 additional quantum features, which might originate from states or Universal Conductance Oscillations in the nanowire bulk, 9 does not allow for a clear identification of the lowest Landau levels at all gate voltages. For both SdH-channels a non-zero S-Berry phase is revealed in the intercepts of the Landau index fan diagram 44 ( Fig.…”

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confidence: 99%

“…Nanowires with a high surface-tovolume ratio are of special interest because the surface state conductivity is expected to overwhelm the parasitic transport through the nanowire bulk. [5][6][7][8][9][10] While the Dirac cone has been directly detected by angle-resolved photoemission spectroscopy (ARPES) of Bi 2 Te 3 , [11][12][13] 20,37,38 While most of these works focus on reducing the relative contribution to electrical transport from the bulk by enhancing the surface contribution via field-effect, resolving the linear dispersion relation of the surface states has not been attempted so far.Our experiments were performed using a single nanowire device equipped with two electrodes for resistance measurements and a global back gate (figure 1 a). Electrical contacts to the nanowire were prepared via common laser beam lithography and subsequent sputter deposition of Ti/Pt.…”

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Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Gooth

Hamdou

Dorn

et al. 2014

Applied Physics Letters

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We validate the linear dispersion relation and resolve the Dirac cone on the surface of a single Bi 2 Te 3 nanowire via a combination of field-effect and magnetoresistance measurements by which we unambiguously prove the topological insulator nature of the nanowire surface states. Moreover we show that the experimentally determined carrier concentration, mobility and cyclotron mass of the surface states are in excellent agreement with relativistic models. Our method provides a facile way to identify topological insulators that too small for angle-resolved photo emission spectroscopy. Unambiguous experimental identification of topological insulators (TIs) requires resolving theDirac cone in the band structure of the non-trivial surface states. [1][2][3][4] Charge carriers within the surface states mimic massless Dirac fermions with extremely high mobilities, opening great opportunities for novel information processing devices. Nanowires with a high surface-tovolume ratio are of special interest because the surface state conductivity is expected to overwhelm the parasitic transport through the nanowire bulk. [5][6][7][8][9][10] While the Dirac cone has been directly detected by angle-resolved photoemission spectroscopy (ARPES) of Bi 2 Te 3 , [11][12][13] 20,37,38 While most of these works focus on reducing the relative contribution to electrical transport from the bulk by enhancing the surface contribution via field-effect, resolving the linear dispersion relation of the surface states has not been attempted so far.Our experiments were performed using a single nanowire device equipped with two electrodes for resistance measurements and a global back gate (figure 1 a). Electrical contacts to the nanowire were prepared via common laser beam lithography and subsequent sputter deposition of Ti/Pt. A highly p-doped silicon chip served as gate with a 200 nm insulating buffer layer of thermal SiO 2 on top. Standard low frequency lock-in techniques were performed in at low temperatures with a magnetic field B applied perpendicular to the current direction along the nanowire axis. Comparing two-terminal and four-terminal measurements reveal that the contact resistances to the nanowire are negligible. Linear IV-curves (SI Fig. 1) demonstrate that the electrical contacts ore ohmic. The Fermi energy of the nanowire was tuned by applying gate voltages between -10 and 30 V in 5 V steps, using a DC voltage source. Bi 2 Te 3 nanowires were grown in a single zone tube furnace on Si/SiO 2 wafers seeded by 30 nm colloidal diameter Au particles, prior to 100 h annealing in a tellurium rich atmosphere at 250 °C. Further details on the nanowire growth as well as on electrical and on structural characterization can be found elsewhere. 8,40 We present data for a single-crystalline, For data analysis we will concentrate on the SdH contribution 'R, which we obtain by subtracting the smooth bulk background and the WAL contribution from R (Fig. 1 d).We observe two dominant transport channels in the SdH spectra by tuning the gate volt...

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Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Gooth

Hamdou

Dorn

et al. 2014

Applied Physics Letters

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“…But it is very difficult to separate residual bulk carrier conduction from surface conduction. Due to crystal defects or thermal excitations bulk carriers dominate the conduction in small bulk bandgap TI materials like Bi 2 Se 3 , thus masking the transport of 2D surface electrons [6,7].…”

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Observation of quantum oscillations in FIB fabricated nanowires of topological insulator (Bi₂Se₃)

Bhattacharyya¹,

Sharma

Awana

et al. 2017

J. Phys.: Condens. Matter

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Since last few years, research based on topological insulators (TI) is in great interests due to intrinsic exotic fundamental properties and future potential applications such as quantum computers or spintronics. The fabrication of TI nanodevices and study on their transport properties mostly focused on high quality crystalline nanowires or nanoribbons. Here we report robust approach of Bi 2 Se 3 nanowire formation from deposited flakes using ion beam milling method. The fabricated Bi 2 Se 3 nanowire devices have been employed to investigate the robustness of topological surface state (TSS) to gallium ion doping and any deformation in the material due to fabrication tools. We report the quantum oscillations in magnetoresistance curves under the parallel magnetic field. The resistance versus magnetic field curves have been studied and compared with Aharonov-Bohm (AB) interference effects which further demonstrate the transport through TSS. The fabrication route and observed electronic transport properties indicate clear quantum oscillations and can be exploited further in studying the exotic electronic properties associated with TI based nanodevices.

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“…One may distinguish between AharonovBohm oscillations with period Φ 0 and Altshuler-AronovSpivak (AAS) oscillations with period Φ 0 /2. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] In addition Universal Conductance Fluctuations (UCFs) are observed -a noise-like component of G(Φ) which depends sensitively on the Fermi level and on disorder. 5,9,[24][25][26][27][28][29][30] TIs also host a Perfectly Conducting Channel (PCC) -a conductance quantum which is remarkable for its persistence in very long TI wires, its topological protection, and its status as a 3-D analogue of the quantum Hall effect.…”

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Quantum interference effects in topological nanowires in a longitudinal magnetic field

Sacksteder

2016

Phys. Rev. B

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We study the magnetoconductance of topological insulator nanowires in a longitudinal magnetic field, including Aharonov-Bohm, Altshuler-Aronov-Spivak, perfectly conducting channel, and universal conductance fluctuation effects. Our focus is on predicting experimental behavior in single wires in the quantum limit where temperature is reduced to zero. We show that changing the Fermi energy EF can tune a wire from from ballistic to diffusive conduction and to localization. In both ballistic and diffusive single wires we find both Aharonov-Bohm and Altshuler-Aronov-Spivak oscillations with similar strengths, accompanied by quite strong universal conductance fluctuations (UCFs), all with amplitudes between 0.3 G0 and 1 G0. This contrasts strongly with the average behavior of many wires, which shows Aharonov-Bohm oscillations in the ballistic regime and AltshulerAronov-Spivak oscillations in the diffusive regime, with both oscillations substantially larger than the conductance fluctuations. In single wires the ballistic and diffusive regimes can be distinguished by varying EF and studying the sign of the AB signal, which depends periodically on EF in ballistic wires and randomly on EF in diffusive wires. We also show that in long wires the perfectly conducting channel is visible at a wide range of energies within the bulk gap. We present typical conductance profiles at several wire lengths, showing that conductance fluctuations can dominate the average signal. Similar behavior will be found in carbon nanotubes. Strong topological insulators (TIs) possess a band gap that can be used to eliminate electrical conduction through their interior, but unlike standard insulators they robustly host conducting surface states which completely wrap all of the TI sample's surfaces.1,2 This unique circumstance allows realization of the celebrated Aharonov-Bohm effect, where electrons are sensitive to the total magnetic flux through a specific loop.3,4 If a TI wire has strictly constant cross-section along the wire's length, and the surface state has strictly zero penetration into the interior, then the wire's conductance G will be a strictly periodic function of the magnetic flux Φ through the wire's cross-section, i.e. G(Φ) = G(Φ + Φ 0 ), where Φ 0 = h/e is the magnetic flux quantum. This periodic dependence on the total magnetic flux threading the electron's path, and not on any local details of the path, is the hallmark of the Aharonov-Bohm (AB) effect.A long string of experiments has realized the AB effect in TI wires, and has observed a zoo of periodic conductance features. One may distinguish between AharonovBohm oscillations with period Φ 0 and Altshuler-AronovSpivak (AAS) oscillations with period Φ 0 /2.5-23 In addition Universal Conductance Fluctuations (UCFs) are observed -a noise-like component of G(Φ) which depends sensitively on the Fermi level and on disorder. 5,9,24-30TIs also host a Perfectly Conducting Channel (PCC) -a conductance quantum which is remarkable for its persistence in very long TI wires, its topological...

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Aharonov-Bohm oscillations and weak antilocalization in topological insulator Sb2Te3 nanowires

Cited by 55 publications

References 28 publications

Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Observation of quantum oscillations in FIB fabricated nanowires of topological insulator (Bi₂Se₃)

Quantum interference effects in topological nanowires in a longitudinal magnetic field

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Aharonov-Bohm oscillations and weak antilocalization in topological insulator Sb2Te3 nanowires

Cited by 55 publications

References 28 publications

Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Resolving the Dirac cone on the surface of Bi2Te3 topological insulator nanowires by field-effect measurements

Observation of quantum oscillations in FIB fabricated nanowires of topological insulator (Bi2Se3)

Quantum interference effects in topological nanowires in a longitudinal magnetic field

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Observation of quantum oscillations in FIB fabricated nanowires of topological insulator (Bi₂Se₃)