Direction-dependent giant optical conductivity in two-dimensional semi-Dirac materials

Mawrie, Alestin; Muralidharan, Bhaskaran

doi:10.1103/physrevb.99.075415

Cited by 28 publications

(32 citation statements)

References 41 publications

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“…The thermal conductivity κ(T ) as a function of temperature T or more precisely κ xx (T )/T and κ yy (T )/T follows from Eqs. (35) and (36) with an additional factor of (ω/T ) 2 included in the integration overω and the factor of electric charge squared is dropped. The Lorenz number L(T ) is related in the usual way to σ dc (T ) and κ(T )/T and is given by…”

Section: Transport: DC Conductivity and Wiedemann-franzmentioning

confidence: 99%

Signatures of merging Dirac points in optics and transport

Ćarbotte

Nicol

2019

Phys. Rev. B

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We consider the optical and transport properties in a model two-dimensional Hamiltonian which describes the merging of two Dirac points. At low energy, in the presence of an energy gap parameter ∆, there are two distinct Dirac points with linear dispersion, these are connected by a saddle point at higher energy. As ∆ goes to zero, the two Dirac points merge and the resulting dispersion exhibits semi-Dirac behaviour which is quadratic in the x-direction ("nonrelativistic") and linear the y-direction ("relativistic"). In the clean limit for each direction (x, y) the contribution of the intraband and interband optical transitions are both given by universal functions of photon energy Ω and chemical potential µ normalized to the energy gap. We provide analytic formulas for both small and large Ω/2∆ and µ/∆ limits. These define, respectively, Dirac and semi-Dirac-like regions.For Ω/2∆ and µ/∆ of order one, there are deviations from these asymptotic behaviors. Considering optics and also transport, such as dc conductivity, thermal conductivity and the Lorenz number, such deviations provide signatures of the evolution from the Dirac to the semi-Dirac regime as the gap ∆ is varied.

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Section: Transport: DC Conductivity and Wiedemann-franzmentioning

confidence: 99%

Signatures of merging Dirac points in optics and transport

Ćarbotte

Nicol

2019

Phys. Rev. B

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“…[41]. The theoretical model used in this paper can be extended to other two-dimensional (2D) Dirac materials [44,45] as well. We obtain the AGF in the diffusive regime using the conductivity model developed by Peres et al [46].…”

Section: Introductionmentioning

confidence: 99%

Graphene as a nanoelectromechanical reference piezoresistor

Sinha

Sharma

Priyadarshi

et al. 2020

Phys. Rev. Research

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Motivated by the recent prediction of anisotropy in piezoresistance of ballistic graphene along longitudinal and transverse directions, we investigate the angular gauge factor of graphene in the ballistic and diffusive regimes using highly efficient quantum transport models. It is shown that the angular gauge factor in both ballistic and diffusive graphene between 0 • to 90 • bears a sinusoidal relation with a periodicity of π due to the reduction of sixfold symmetry into a twofold symmetry as a result of applied strain. The angular gauge factor is zero at critical angles 20 • and 56 • in ballistic and diffusive regimes, respectively. Based on these findings, we propose a graphene-based ballistic nanosensor which can be used as a reference piezoresistor in a Wheatstone bridge readout technique. The reference sensors proposed here are unsusceptible to inherent residual strain present in strain sensors and unwanted strain generated by the vapors in explosives detection. The theoretical models developed in this paper can be applied to explore similar applications in other two-dimensional Dirac materials. The proposals made here potentially pave the way for implementation of nanoelectromechanical strain sensors based on the principle of ballistic transport, which will eventually replace conventional microelectromechanical piezoresistance sensors with a decrease in feature size. The presence of strain-insensitive "critical angle" in graphene may be useful in flexible wearable electronics also.

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“…В настоящее время интерес вызывает исследование анизотропных моделей дираковских кристаллов [9][10][11][12][13]. Так, например, в лабораторных условиях получены так называемые полудираковские кристаллы [14], где движению носителей заряда вдоль одной кристаллографической оси соответствует квадратичная дисперсия, а движению вдоль другой -линейная или гиперболическая дисперсия.…”

Section: Introductionunclassified

Фотоиндуцированное Состояние Флоке-Изолятора В Графеноподобном Кристалле

Кухарь¹,

Крючков²

2022

Журнал Технической Физики

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Floquet spectrum of charge carriers in a 2D crystal with initially displaced Dirac points has been derived. The phase and amplitude dependences of the energy gap induced by elliptically polarized and bichromatic high-frequency fields has been investigated. In contrast to graphene the linearly polarized electric field has been shown to be able to transform the initially semi-metallic state of Dirac crystal into the Floquet-insulator state. The conditions for such a transition are indicated, one of which is the mismatch between the orientation of the field polarization line and the direction of the crystallographic axes.

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Direction-dependent giant optical conductivity in two-dimensional semi-Dirac materials

Cited by 28 publications

References 41 publications

Signatures of merging Dirac points in optics and transport

Signatures of merging Dirac points in optics and transport

Graphene as a nanoelectromechanical reference piezoresistor

Фотоиндуцированное Состояние Флоке-Изолятора В Графеноподобном Кристалле

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