Measurement of topological Berry phase in highly disordered graphene

Bennaceur, Keyan; Guillemette, Jonathan; Lévesque, Pierre L.; Cottenye, Nicolas; Mahvash, Farzaneh; Hemsworth, N.; Kumar, Abhishek; Murata, Yuya; Heun, S.; Goerbig, M. O.; Proust, Cyril; Siaj, Mohamed; Martel, Richard; Gervais, G.; Szkopek, Thomas

doi:10.1103/physrevb.92.125410

Cited by 12 publications

(10 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1a) for the representative sample HG18. Strong insulating behaviour, ∂R 2pt /∂T < 0, is observed, indicative of the onset of electron localization by the introduction of neutral point defects into the graphene lattice via hydrogenation, as previously reported [3,4,24,26]. The field effect corresponds to hole conduction, ∂R 2pt /∂V G > 0, with a field effect mobility µ ∝ ∂(1/R)/∂V G → 0 as T → 0.…”

supporting

confidence: 78%

“…Atomic hydrogen adsorbates create C-H bonds that disrupt the sp 2 lattice of graphene to create localized sp 3 distortions, with a profound effect on graphene's electronic properties [24,25]. The neutral point defect density per carbon atom induced by hydrogenation in our samples is on the order of parts per thousand, as inferred from Raman spectroscopy [3,4,26]. Direct experimental evidence for band gap opening and the appearance of localized states in hydrogenated graphene has reported using angle-resolved photoemission spectroscopy (ARPES) and scanning tunnelling spectroscopy [28][29][30][31].…”

mentioning

confidence: 84%

“…Here, we report the experimental discovery of a positive, in-plane magnetoresistance (MR) reaching 235% in hydrogenated graphene, which we term large magnetoresistance (LMR). Similar hydrogenated graphene samples have shown a strong negative MR with magnetic field applied normal to the sample surface, corresponding to a transition from an insulating state to a quantum Hall state [3,4]. The MR of a variety of functionalized graphene systems with magnetic field applied normal to the graphene surface has been explored [5][6][7].…”

mentioning

confidence: 99%

“…The model of Matveev et al assumes a constant density of localized states, thus leading to a temperature dependent conductivity σ xx = σ 0 exp −(T /T 0 ) 1/d+1 F (x) , where d = 2, 3 is the dimension of the conductor, T 0 is the characteristic Mott temperature, and F (x) is a universal function of a dimensionless magnetic field parameter x = µ B B/k B T (T 0 /T ) 1/d+1 . Experimentally measured hydrogenated graphene resistivity does not follow a simple Mott variable range hopping law [3,4,26] (see Supplemental Material [33]). The measured resistance of HGT2 in logarithmic scale versus reciprocal temperature 1/T at zero magnetic field is shown in Fig.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Large magnetoresistance by Pauli blockade in hydrogenated graphene

et al. 2018

Self Cite

View full text Add to dashboard Cite

We report the observation of a giant positive magnetoresistance in millimetre scale hydrogenated graphene with magnetic field oriented in the plane of the graphene sheet. A positive magnetoresistance in excess of 200% at a temperature of 300 mK was observed in this configuration, reverting to negative magnetoresistance with the magnetic field oriented normal to the graphene plane. We attribute the observed positive, in-plane, magnetoresistance to Pauli-blockade of hopping conduction induced by spin polarization. Our work shows that spin polarization in concert with electron-electron interaction can play a dominant role in magnetotransport within an atomic monolayer.

show abstract

supporting

confidence: 78%

mentioning

confidence: 84%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Large magnetoresistance by Pauli blockade in hydrogenated graphene

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The topological contribution to the Berry phase [34], which is basically a winding number of the pseudospin 1/2 [35,36], is predicted to be more robust under disorder, as it should persist even in the presence of sublattice symmetry breaking and associated gap opening. Such behavior has been demonstrated experimentally in hydrogenated graphene [37]. Also, a robust QHE is expected in graphene, even when strong impurities are at a distance smaller than the magnetic length from each other.…”

Section: Introductionmentioning

confidence: 72%

Unconventional features in the quantum Hall regime of disordered graphene: Percolating impurity states and Hall conductance quantization

et al. 2016

View full text Add to dashboard Cite

We report on the formation of critical states in disordered graphene, at the origin of variable and unconventional transport properties in the quantum Hall regime, such as a zero-energy Hall conductance plateau in the absence of an energy band gap and Landau-level degeneracy breaking. By using efficient real-space transport methodologies, we compute both the dissipative and Hall conductivities of large-size graphene sheets with random distribution of model single and double vacancies. By analyzing the scaling of transport coefficients with defect density, system size, and magnetic length, we elucidate the origin of anomalous quantum Hall features as magnetic-fielddependent impurity states, which percolate at some critical energies. These findings shed light on unidentified states and quantum-transport anomalies reported experimentally.

show abstract

Driven dissipative dynamics and topology of quantum impurity systems

Hur

Henriet

Herviou

et al. 2018

Comptes Rendus. Physique

View full text Add to dashboard Cite

In this review, we provide an introduction and overview to some more recent advances in real-time dynamics of quantum impurity models and their realizations in quantum devices. We focus on the Ohmic spin-boson and related models, which describes a single spin-1/2 coupled to an infinite collection of harmonic oscillators. The topics are largely drawn from our efforts over the past years, but we also present a few novel results. In the first part of this review, we begin with a pedagogical introduction to the real-time dynamics of a dissipative spin at both high and low temperatures. We then focus on the driven dynamics in the quantum regime beyond the limit of weak spin-bath coupling. In these situations, the non-perturbative stochastic Schroedinger equation method is ideally suited to numerically obtain the spin dynamics as it can incorporate bias fields h z (t) of arbitrary time-dependence in the Hamiltonian. We present different recent applications of this method: (i) how topological properties of the spin such as the Berry curvature and the Chern number can be measured dynamically, and how dissipation affects the topology and the measurement protocol, (ii) how quantum spin chains can experience synchronization dynamics via coupling to a common bath. In the second part of this review, we discuss quantum engineering of spin-boson and related models in circuit quantum electrodynamics (cQED), quantum electrical circuits and cold-atoms architectures. In different realizations, the Ohmic environment can be represented by a long (microwave) transmission line, a Luttinger liquid, a one-dimensional Bose-Einstein condensate, a chain of superconducting Josephson junctions. We show that the quantum impurity can be used as a quantum sensor to detect properties of a bath at minimal coupling, and how dissipative spin dynamics can lead to new insight in the Mott-Superfluid transition.

show abstract

Measurement of topological Berry phase in highly disordered graphene

Cited by 12 publications

References 39 publications

Large magnetoresistance by Pauli blockade in hydrogenated graphene

Large magnetoresistance by Pauli blockade in hydrogenated graphene

Unconventional features in the quantum Hall regime of disordered graphene: Percolating impurity states and Hall conductance quantization

Driven dissipative dynamics and topology of quantum impurity systems

Contact Info

Product

Resources

About