24 h stability of thick multilayer silicene in air

Padova, Paola De; Ottaviani, Carlo; Quaresima, C.; Olivieri, Bruno; Imperatori, P.; Salomon, Éric; Angot, Thierry; Quagliano, Lucia G.; Romano, Claudia; Vona, Alessandro; Muniz‐Miranda, Maurizio; Generosi, Amanda; Paci, Barbara; Lay, G. Le

doi:10.1088/2053-1583/1/2/021003

Cited by 138 publications

(174 citation statements)

References 52 publications

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“…These effects also have been observed in 'Dirac materials' such as graphene [4,5,9]. and are expected to be present in other graphene-like materials [6][7][8] with novel attributes. The FQHE states in monolayer and bilayer graphene were investigated theoretically [9][10][11][12] and experimentally [13,14].…”

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confidence: 72%

Missing fractional quantum Hall states in ZnO

Luo

Chakraborty

2016

Phys. Rev. B

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We have analyzed the crucial role the Coulomb interaction strength plays on the even and odd denominator fractional quantum Hall effects in a two-dimensional electron gas (2DEG) in the ZnO heterointerface. In this system, the Landau level gaps are much smaller than those in conventional GaAs systems. The Coulomb interaction is also very large compared to the Landau level gap even in very high magnetic fields. We therefore consider the influence of higher Landau levels by considering the screened Coulomb potential in the random phase approximation. Interestingly, our exact diagonalization studies of the collective modes with this screened potential successfully explain recent experiments of even and odd denominator fractional quantum Hall effects, in particular, the unexpected absence of the 5/2 state and the presence of 9/2 state in ZnO.Discovery of the odd-denominator fractional quantum Hall effects (FQHE) in GaAs heterojunctions in 1982 [1] and its subsequent explanation by Laughlin [2,3], has remained the 'gold standard' for novel quantum states of correlated electrons in a strong magnetic field. These effects also have been observed in 'Dirac materials' such as graphene [4,5,9]. and are expected to be present in other graphene-like materials [6][7][8] with novel attributes. The FQHE states in monolayer and bilayer graphene were investigated theoretically [9][10][11][12] and experimentally [13,14]. For example, in bilayer graphene the application of a bias voltage results in some Landau levels (LLs) a phase transition between incompressible FQHE and compressible phases [11,12]. The FQHE in silicene and germanene indicated that because of the strong spinorbit interaction present in these materials as compared to graphene, the electron-electron interaction and the FQHE gap are significantly modified [15]. The puckered structure of phosphorene exhibits a lower symmetry than graphene. This results in anisotropic energy spectra and other physical characteristics of phosphorene, both in momentum and real space in the two-dimensional (2D) plane [16,17]. The anisotropic band structure of phosphorene causes splitting of the magnetoroton mode into two branches with two minima. For long wavelengths, we also found a second mode with upward dispersion that is clearly separated from the magnetoroton mode and is entirely due to the anisotropic bands [18].In 1987, a discovery of the quantum Hall state at the LL filling factor ν = 5 2 , the first even-denominator state observed in a single-layer system [19] added to the mystery of the FQHE. It soon became clear that this state must be different from the FQHE in predominantly odd-denominator filling fractions [1]. Understanding this enigmatic state has remained a major challenge in all these years [20,21]. At this half-filled first excited LL, a novel state described by a pair wave function involving a Pfaffian [12,22], where the low-energy excitations obey non-Abelian exchange statistics, has been the strongest * Tapash.Chakraborty@umanitoba.ca candidate.The field of FQHE has...

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confidence: 72%

Missing fractional quantum Hall states in ZnO

Luo

Chakraborty

2016

Phys. Rev. B

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“…Since then, there has been a growing interest in the production of other low-dimensional crystals. The investigation of analogs of graphene has resulted in the discovery of several single-layer crystals of different elements, such as silicon (silicene) [2] and germanium (germanene) [3], as well as a class of materials known as transition-metal dichalcogenides [4]. Some of these materials may soon find use in electronic devices, mainly due to the fact that in contrast to graphene, they present a band gap in their electronic spectrum, albeit with a lower carrier mobility.…”

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confidence: 99%

Landau levels of single-layer and bilayer phosphorene

2015

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In this work we introduce a low-energy Hamiltonian for single-layer and bilayer black phosphorus that describes the electronic states at the vicinity of the point. The model is based on a recently proposed tight-binding description for electron and hole bands close to the Fermi level. We calculate expressions for the Landau-level spectrum as function of magnetic field, and in the case of bilayer black phosphorus we investigate the effect of an external bias on the electronic band gap. The results showcase the highly anisotropic character of black phosphorus, and in particular for bilayer BP, the presence of bias allows for a field-induced semiconductor-metal transition.

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“…Although there are external means to create band gap in graphene, such as application of a bias voltage to bilayer graphene, in the past few years intense search has been undertaken to find other 2D materials, which in addition to exhibiting mobilities close to graphene, also posses a considerable band gap in their normal state. There were several Dirac materials, such as silicene [3], germanene [4], MoS 2 and other group-VI transition-metal dichalcogenides [5] that have been lately explored and promising results were observed.In the past year another material which has gained popularity in this context, is the 2D version of black phosphorus (BP) [6][7][8][9][10], the single layer of BP known as phosphorene. BP is the most stable allotrope of Phosphorus at room temperature and pressure.…”

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confidence: 99%

Aspects of anisotropic fractional quantum Hall effect in phosphorene

Ghazaryan

Chakraborty

2015

Phys. Rev. B

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We have analyzed the effects of the anisotropic energy bands of phosphorene on magnetoroton branches for electrons and holes in the two Landau levels close to the band edges. We have found that the fractional quantum Hall effect gap in the lowest (highest) Landau level in conduction (valence) band is slightly larger than that for conventional semiconductor systems and therefore experimentally observable. We also found that the magnetoroton mode for both electrons and holes consists of two branches with two minima due to the anisotropy. Additionally, we show that due to the anisotropy, there is a second mode with positive dispersion, well separated from the magnetoroton mode for small wave vectors. These novel features of the collective mode can be observed in resonant inelastic light scattering experiments.With the advent of graphene [1, 2] the two dimensional (2D) materials have gained renewed attention during the last decade because of their remarkable electronic, optical and mechanical properties and for potential device applications. Practical application of graphene in electronic devices is however limited due to its zero band gap. Although there are external means to create band gap in graphene, such as application of a bias voltage to bilayer graphene, in the past few years intense search has been undertaken to find other 2D materials, which in addition to exhibiting mobilities close to graphene, also posses a considerable band gap in their normal state. There were several Dirac materials, such as silicene [3], germanene [4], MoS 2 and other group-VI transition-metal dichalcogenides [5] that have been lately explored and promising results were observed.In the past year another material which has gained popularity in this context, is the 2D version of black phosphorus (BP) [6][7][8][9][10], the single layer of BP known as phosphorene. BP is the most stable allotrope of Phosphorus at room temperature and pressure. Few-layer BP can be obtained through mechanical exfoliation method akin to graphene. However, unlike graphene the BP layers are not perfectly flat. Due to the sp 3 hybridization of 3s and 3p atomic orbitals the layers of BP form a puckered surface. The band gap of BP depends on the number of layers of the sample, and it ranges from 0.3 eV in the bulk case at the Z point in the Brillouin zone to 1.5 -2 eV for few layer and monolayer case at the Γ point. The mobilities of the few-layer BP obtained so far lie in the range of 1000 -5000 cm 2 V −1 s −1 [6,11,12]. Considerable progress has been made in the study of the electronic and optical properties of this material both experimentally [6][7][8][11][12][13] and theoretically [14][15][16][17][18][19][20][21][22][23][24]. Higher mobilities were achieved by sandwiching the BP in hexagonal boron nitride flakes and placing on top of the graphite back gate that has enabled observation of the integer quantum Hall effect [12]. Clearly the next step in the experimental progress is to reach the regime where the fractional * Tapash.Chakraborty@umanitoba.ca quan...

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24 h stability of thick multilayer silicene in air

Cited by 138 publications

References 52 publications

Missing fractional quantum Hall states in ZnO

Missing fractional quantum Hall states in ZnO

Landau levels of single-layer and bilayer phosphorene

Aspects of anisotropic fractional quantum Hall effect in phosphorene

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