Localization and the Kosterlitz-Thouless Transition in Disordered Graphene

Zhang, Yanyang; Hu, Jiangping; Bernevig, B. Andrei; Wang, Xiang Rong; Xie, X. C.; Liu, Wu-Ming

doi:10.1103/physrevlett.102.106401

Cited by 174 publications

(126 citation statements)

References 37 publications

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“…We consider two types of puddles with similar mobilities µ ≈ 10 4 cm 2 /Vs but different values of π i.v : U p = 0.5 eV and conc = 1%, versus U p = 1.4 eV and conc = 0.1%, with ratio π i.v 1000 and 160 respectively. 35 We also consider a third type of puddle with U p = 2.8 eV and conc = 0.1%, which has a lower mobility µ ≈ 1000 cm 2 /Vs and a much smaller value of π i.v = 5 . In Fig.…”

Section: Resultsmentioning

confidence: 99%

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Spin Hall Effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures

2017

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We report on a theoretical study of the spin Hall Effect (SHE) and weak antilocalization (WAL) in graphene/transition metal dichalcogenide (TMDC) heterostructures, computed through efficient real-space quantum transport methods, and using realistic tight-binding models parametrized from ab initio calculations. The graphene/WS 2 system is found to maximize spin proximity effects compared to graphene on MoS 2 , WSe 2 , or MoSe 2 , with a crucial role played by disorder, given the disappearance of SHE signals in the presence of strong intervalley scattering. Notably, we found that stronger WAL effects are concomitant with weaker charge-to-spin conversion efficiency. For further experimental studies of graphene/TMDC heterostructures, our findings provide guidelines for reaching the upper limit of spin current formation and for fully harvesting the potential of two-dimensional materials for spintronic applications.

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Section: Resultsmentioning

confidence: 99%

“…This is due to the modification of the band structure, which becomes slightly more massive and therefore favors backscat-tering. 35 Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

Spin Hall Effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures

2017

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“…In the dilute limit, τ p and τ iv are inversely proportional to the number of scatterers N , while controls their relative magnitude, with larger giving stronger intervalley scattering [40,41].…”

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confidence: 99%

Giant Spin Lifetime Anisotropy in Graphene Induced by Proximity Effects

et al. 2017

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We report on fundamental aspects of spin dynamics in heterostructures of graphene and transition metal dichalcogenides (TMDCs). By using realistic models derived from first principles we compute the spin lifetime anisotropy, defined as the ratio of lifetimes for spins pointing out of the graphene plane to those pointing in the plane. We find that the anisotropy can reach values of tens to hundreds, which is unprecedented for typical 2D systems with spin-orbit coupling and indicates a qualitatively new regime of spin relaxation. This behavior is mediated by spin-valley locking, which is strongly imprinted onto graphene by TMDCs. Our results indicate that this giant spin lifetime anisotropy can serve as an experimental signature of materials with strong spin-valley locking, including graphene/TMDC heterostructures and TMDCs themselves. Additionally, materials with giant spin lifetime anisotropy can provide an exciting platform for manipulating the valley and spin degrees of freedom, and for designing novel spintronic devices. [3,4], where the combined system might be engineered for specific applications [5] or might enable the exploration of new phenomena [6,7]. In the field of spintronics, graphene has exceptional charge transport properties but weak spin-orbit coupling (SOC) on the order of 10 µeV [8], which makes it ideal for long-distance spin transport [9-11] but ineffective for generating or manipulating spin currents. To advance towards spin manipulation, recent work has focused on heterostructures of graphene and magnetic insulators [12][13][14][15][16] or strong SOC materials such as transition metal dichalcogenides (TMDCs) and topological insulators [17][18][19]. The SOC induced in graphene by a TMDC could enable phenomena such as topological edge states [20] or the spin Hall effect [21][22][23].To this end, a variety of recent experiments have explored spin transport in graphene/TMDC heterostructures [21,[24][25][26][27][28][29]. Magnetotransport measurements revealed that graphene in contact with WS 2 exhibits a large weak antilocalization (WAL) peak, revealing a strong SOC induced by proximity effects [24][25][26]30]. Fits to the magnetoconductance yielded spin lifetimes τ s ≈ 5 ps, which is two to three orders of magnitude lower than graphene on traditional substrates [10,31]. It was later asserted that after the removal of a temperatureindependent background, τ s becomes at most only a few hundred femtoseconds [26]. Nonlocal Hanle measurements, meanwhile, have revealed spin lifetimes up to a few tens of picoseconds [27][28][29] that can be tuned by a back gate [28,29]. Finally, charge transport measure-

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“…Their striking properties lie in the robust surface states that are observed by angleresolved photoemission spectroscopy. Moreover, TI has become the origin of a number of interesting quantum phenomena such as the quantum anomalous Hall effect [14][15][16][17][18][19][20][21][22], Majorana fermions [23,24], and the topological magnetoelectric effect [4]. In two-dimensional (2D) systems, the quantum Hall effect emerges due to magnetic-field-induced Landau quantization.…”

Section: Introductionmentioning

confidence: 99%

Tunable topological quantum states in three- and two-dimensional materials

2015

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We review our theoretical advances in tunable topological quantum states in three-and twodimensional materials with strong spin-orbital couplings. In three-dimensional systems, we propose a new tunable topological insulator, bismuth-based skutterudites in which topological insulating states can be induced by external strains. The orbitals involved in the topological band-inversion process are the d-and p-orbitals, unlike typical topological insulators such as Bi 2 Se 3 and BiTeI, where only the p-orbitals are involved in the band-inversion process. Owing to the presence of large d-electronic states, the electronic interaction in our proposed topological insulator is much stronger than that in other conventional topological insulators. In two-dimensional systems, we investigated 3d-transition-metal-doped silicene. Using both an analytical model and first-principles Wannier interpolation, we demonstrate that silicene decorated with certain 3d transition metals such as vanadium can sustain a stable quantum anomalous Hall effect. We also predict that the quantum valley Hall effect and electrically tunable topological states could be realized in certain transition-metal-doped silicenes where the energy band inversion occurs. These findings provide realistic materials in which topological states could be arbitrarily controlled.

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Localization and the Kosterlitz-Thouless Transition in Disordered Graphene

Cited by 174 publications

References 37 publications

Spin Hall Effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures

Spin Hall Effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures

Giant Spin Lifetime Anisotropy in Graphene Induced by Proximity Effects

Tunable topological quantum states in three- and two-dimensional materials

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