Unconventional Transport through Graphene on SrTiO3: A Plausible Effect of SrTiO3 Phase-Transitions

Saha, Surajit; Kahya, Orhan; Jaiswal, Manu; Srivastava, Amar; Annadi, Anil; Balakrishnan, Jayakumar; Pachoud, Alexandre; Toh, Chee Tat; Hong, Byung Hee; Ahn, Jong Hyun; Venkatesan, T.; Özyilmaz, Barbaros

doi:10.1038/srep06173

Cited by 32 publications

(50 citation statements)

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“…In general, the hysteresis increases as the sweeping range and the rate increase. Unlike previous reports of hysteresis observed in different graphene devices, [49][50][51][52][53] origin of hysteresis in our device is not clear. A more detailed discussion of the hysteresis and possible causes are described in Supporting Information.…”

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confidence: 99%

Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO₃/SrTiO₃ Heterostructures

et al. 2017

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2Weak localization (WL) and weak antilocalization (WAL) are quantum interference effects [1][2][3][4] resulting from electron phase coherence and spin-orbit interactions in 2-dimensional (2D) electron systems. WL results from constructive interference between pairs of time-reversed closed-loop electron trajectories and provides a positive correction to the Drude resistivity. [2, 4] Spin-orbit coupling (SOC) leads to suppressed backscattering due to destructive interference, leading to WAL and a negative correction to the Drude resistivity.[3]The intrinsic SOC of graphene is weak; [5] however, charge carriers in graphene possess a pseudospin degree of freedom, which arises from the degeneracy introduced by the two inequivalent atomic sites per unit cell in the graphene honeycomb lattice being comprised of A and B sublattices[ Figure 1(a) and (b)]. [6, 7] Recent discovery of unique quantum transport phenomena in graphene, such as unconventional half-integer quantum Hall effect [7, 8] and Klein tunneling [9][10][11] is a direct consequence of non-trivial Berry phase of ! induced by pseudospin rotation. Pseudospin in graphene can be utilized to store and manipulate information, which is analogous to the spin degree of freedom in spintronics. [12][13][14][15][16] Because of pseudospin rotation, each scattering process has a phase difference of ! between two time reversal pair in a closed quantum diffusive path. This results in destructive interference that suppresses backscattering, leading to WAL in graphene, which is analogous to the role of SOC (Figure 1(c) and (d)) in ordinary semiconductors. WAL is theoretically expected in graphene in the absence of inter-valley and chirality breaking scattering. [17] Most studies have not presented clear evidence of WAL via negative magnetoconductance, [18][19][20][21][22] most likely due to presence of point defects in graphene samples that locally break the sublattice degeneracy and smooth out !-phase contribution. Experimental signatures of WAL observed in high-quality epitaxial graphene samples are attributed to suppressed point defects.[23]Interestingly, a WL to WAL transition is achieved in high quality exfoliated samples [24] by decreasing the ratio of the dephasing length to the symmetry-breaking length via decoherence and carrier-density control. 3Preservation of pseudospin quantum interference up to room temperature (RT) is of fundamental importance for a variety of proposed applications, [12-16, 25, 26] but thermal perturbations typically suppress the phase coherence and hinder practical use of the devices. RT operation can be achieved if the high graphene mobility is consistently maintained over a broad temperature range and phonon-scattering contribution is significantly reduced. The mobility of graphene field-effect devices fabricated on SiO 2 /Si substrates is typically reduced at RT due to scattering with surface polar modes. [20,27,28] A significant improvement in quality was achieved by fabricating graphene devices on hexagonal-boron nitride (hBN) ...

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Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO₃/SrTiO₃ Heterostructures

et al. 2017

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“…At room temperature none of the carriers have sufficient energy to transfer from valence band to conduction band so there are no free carriers. At elevated temperature some electrons acquired sufficient energy to reach the conduction band [37][38][39][40]. These results in a thermally generated electron-hole pair in intrinsic region of graphene and subsequently generate a current, driven by an electrostatic potential difference.…”

Section: Morphology Of Graphene-p(vdf-trfe) Self-powered Thermistormentioning

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Self-powered graphene thermistor

et al. 2016

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“…To point possible realizations of these states we provide few examples in realistic materials such as graphene in an optical cavity [26] or graphene on top of a substrate with active phonon modes, e.g. SrTiO 3 (STO) [27][28][29]. We prove that the induced interactions originating from intrinsic longitudinal and transverse optical phonon modes of graphene have opposite effect on low-energy dispersion of graphene; so that the net self-energy correction vanishes.…”

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confidence: 99%

Helical metals and insulators: Sheet singularity of the inflated Berry monopole

2018

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FIG. 1: Helical metal and insulator. (color online) Panels (a)-(c) Characterization of Dirac cones (k• = 0), helical insulators (k• > 0) and helical metals (k• < 0) in terms of the excitation spectrum. Different colors of cones stand for the opposite helicity. The corresponding density of states (DOS) is shown in panels (d)-(f) in units of ρ d = 2π(2π v) −d . We set here ∆ = ±1. Helical insulators are characterized by the opening of a massless gap, whereas helical metals present a Dirac cone crossing. Panel (g-h): topology of nodal circle and nodal sphere in two and three-dimensions, respectively, as induced by the Lifshitz transition (see text).arXiv:1808.06594v1 [cond-mat.str-el]

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Unconventional Transport through Graphene on SrTiO3: A Plausible Effect of SrTiO3 Phase-Transitions

Cited by 32 publications

References 33 publications

Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO₃/SrTiO₃ Heterostructures

Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO₃/SrTiO₃ Heterostructures

Self-powered graphene thermistor

Helical metals and insulators: Sheet singularity of the inflated Berry monopole

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Unconventional Transport through Graphene on SrTiO3: A Plausible Effect of SrTiO3 Phase-Transitions

Cited by 32 publications

References 33 publications

Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO3/SrTiO3 Heterostructures

Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO3/SrTiO3 Heterostructures

Self-powered graphene thermistor

Helical metals and insulators: Sheet singularity of the inflated Berry monopole

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Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO₃/SrTiO₃ Heterostructures

Room‐Temperature Quantum Transport Signatures in Graphene/LaAlO₃/SrTiO₃ Heterostructures