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Grbić, Boris; Leturcq, R.; Ihn, Thomas; Ensslin, Klaus; Reuter, D.; Wieck, A. D.

doi:10.1103/physrevb.77.125312

“…Therefore the relation τ so > τ e may not be valid here. We expect WAL to be suppressed due to reduced backscattering and the WAL peak to be narrower, resulting from the higher mobility in these samples (a similar behavior has been observed in GaAs heterostructures [30]). Therefore the absence of WAL in these samples is not indicative of a lower SOC strength.…”

Section: B Ballistic Regimesupporting

confidence: 64%

Magnetotransport in heterostructures of transition metal dichalcogenides and graphene

Völkl

¹

,

Rockinger

²

,

Drienovsky

³

et al. 2017

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We use a van der Waals pickup technique to fabricate different heterostructures containing WSe 2 (WS 2 ) and graphene. The heterostructures were structured by plasma etching, contacted by one-dimensional edge contacts, and a top gate was deposited. For graphene/WSe 2 /SiO 2 samples we observe mobilities of ∼12 000 cm 2 V −1 s −1 . Magnetic-field-dependent resistance measurements on these samples show a peak in the conductivity at low magnetic fields. This dip is attributed to the weak antilocalization (WAL) effect, stemming from spin-orbit coupling. Samples where graphene is encapsulated between WSe 2 (WS 2 ) and hexagonal boron nitride show a much higher mobility of up to ∼120 000 cm 2 V −1 s −1 . However, in these samples no WAL peak can be observed. We attribute this to a transition from the diffusive to the quasiballistic regime. At low magnetic fields a resistance peak appears, which we ascribe to a size effect due to boundary scattering. Shubnikov-de Haas oscillations in fully encapsulated samples show all integer filling factors due to complete lifting of the spin and valley degeneracies.

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“…In disordered materials, weak localization (WL) arises from constructive interference between time-reversed partial waves of the charge carriers. This leads to an enhanced probability of carrier backscattering, enhancing resistivity 4 – 7 . This interference effect is relevant for diffusive orbits up to the length scale of the phase-coherence length l ϕ .…”

Section: Introductionmentioning

confidence: 99%

Weak antilocalization, spin–orbit interaction, and phase coherence length of a Dirac semimetal Bi0.97Sb0.03

Salawu

¹

,

Yun

²

,

Rhyee

³

et al. 2022

Sci Rep

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The present study develops a general framework for weak antilocalization (WAL) in a three-dimensional (3D) system, which can be applied for a consistent description of longitudinal resistivity $$\rho_{xx} \left( B \right)$$ ρ xx B and Hall resistivity $$\rho_{xy} \left( B \right)$$ ρ xy B over a wide temperature (T) range. Compared to the previous approach Vu et al. (Phys Rev B 100:125162, 2019), which assumes infinite phase coherence length (lϕ) and a zero spin–orbit scattering length (lSO), the present framework is more general, covering high T and the intermediate spin–orbit coupling strength. Based on the new approach, the $$\rho_{xx} \left( B \right)$$ ρ xx B and $$\rho_{xy} \left( B \right)$$ ρ xy B of the Dirac semimetal Bi0.97Sb0.03 was analyzed over a wide T range from 1.7 to 300 K. The present framework not only explains the main features of the experimental data but also enables one to estimate lϕ and lSO at different temperatures. The lϕ has a power-law T dependence at high T and saturates at low T. In contrast, the lSO shows negligible T dependence. Because of the different T dependence, a crossover occurs from the lSO-dominant low-T to the lϕ-dominant high-T regions. Accordingly, the hallmark features of weak antilocalization (WAL) in $$\rho_{xx} \left( B \right)$$ ρ xx B and $$\rho_{xy} \left( B \right)$$ ρ xy B are gradually suppressed across the crossover with increasing T. The present theory describes both low-T and high-T regions successfully, which is impossible in the previous approximate approach. This work offers insights for understanding quantum electrical transport phenomena and their underlying physics, particularly when multiple WAL length scales are competing.

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“…In addition, the presence of the etched trenches around the ring allows an easier lateral penetration of the field lines coming from the top gate and thus leads to an improved tunability of the ring density compared to the bulk. For this reason we believe that tuning the ring with a top gate is similar to tuning it with side gates: in both cases the gates mainly change the Fermi energy and any change in the SOI has to be attributed predominantly to the change in the holes density rather than to the change of the external electric field [2,4]. Figure 1(a) shows a typical magnetoresistance measurement of the ring, figure 1(e) shows its Fourier transform.…”

Section: Resultsmentioning

confidence: 99%

“…In the light of these results, the unambiguous identification of SOI-induced phase effects in AB rings remains still an open and challenging experimental task. Gesellschaft interaction and SOI [2,3]. A two-dimensional hole gas (2DHG) in the valence band of GaAs is characterized by wave functions whose symmetry is reminiscent of atomic p-orbitals.…”

mentioning

confidence: 99%

Aharonov–Bohm rings with strong spin–orbit interaction: the role of sample-specific properties

Nichele

¹

,

Komijani

²

,

Hennel

³

et al. 2013

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We present low-temperature transport experiments on Aharonov-Bohm (AB) rings fabricated from two-dimensional hole gases in p-type GaAs/AlGaAs heterostructures. Highly visible h/e (up to 15%) and h/2e oscillations, present for different gate voltages, prove the high quality of the fabricated devices. Like in previous work, a clear beating pattern of the h/e and h/2e oscillations is present in the magnetoresistance, producing split peaks in the Fourier spectrum. The magnetoresistance evolution is presented and discussed as a function of temperature and gate voltage. It is found that sample specific properties have a pronounced influence on the observed behaviour. For example, the interference of different transverse modes or the interplay between h/e oscillations and conductance fluctuations can produce the features mentioned above. In previous work they have occasionally been interpreted as signatures of spin-orbit interaction (SOI)-induced effects. In the light of these results, the unambiguous identification of SOI-induced phase effects in AB rings remains still an open and challenging experimental task. Gesellschaft interaction and SOI [2,3]. A two-dimensional hole gas (2DHG) in the valence band of GaAs is characterized by wave functions whose symmetry is reminiscent of atomic p-orbitals. Due to the non-zero angular momentum and to the confinement in the growth direction, carriers are effectively described as spin 3/2 particles, for which SOI corrections (cubic in the momentum) are expected to be stronger than for their electronic counterpart [4]. Furthermore, holes in GaAs have a very high effective mass, several times larger than that of the electrons in the conduction band. The smaller Fermi energy makes the carrier-carrier Coulomb interactions more pronounced, allowing the study of many-body related effects.It is predicted that, in a ring-shaped nanostructure penetrated by a magnetic field, the strong SOI would induce, in addition to the conventional AB phase [5], a second geometrical phase term. This additional term, that in the adiabatic limit is commonly referred to as a Berry phase, acts on the spin part of the particle wave function [6][7][8][9][10][11]. The interplay between AB phase and geometrical phase is expected to result in a complex beating-like behaviour of the oscillatory magnetoresistance [12][13][14][15].Previous work with AB rings fabricated in materials with strong SOI, including p-type GaAs, showed such a beating pattern which was interpreted as being related to the occurrence of the predicted Berry phase [16][17][18][19]. Other experiments [20][21][22] focused on the modulation of the AB phase at zero magnetic field produced by changing the electrostatic potential in the ring and were interpreted in terms of the Aharonov-Casher effect [23]. In this work we present data on AB rings embedded in p-type 2DHGs. A fabrication technology, slightly different from the work reported in [19], allows a much larger electrical tunability. The overall quality of the fabricated rings is demonstrated by...

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Strong spin-orbit interactions and weak antilocalization in carbon-dopedp-typeGaAs∕AlxGa1<

Cited by 64 publications

References 33 publications

Magnetotransport in heterostructures of transition metal dichalcogenides and graphene

Magnetotransport in heterostructures of transition metal dichalcogenides and graphene

Weak antilocalization, spin–orbit interaction, and phase coherence length of a Dirac semimetal Bi0.97Sb0.03

Aharonov–Bohm rings with strong spin–orbit interaction: the role of sample-specific properties

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