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Conductance fluctuations in high mobility monolayer graphene: Nonergodicity, lack of determinism and chaotic behavior

View Article: PubMed Central - PubMed

ABSTRACT

We have fabricated a high mobility device, composed of a monolayer graphene flake sandwiched between two sheets of hexagonal boron nitride. Conductance fluctuations as functions of a back gate voltage and magnetic field were obtained to check for ergodicity. Non-linear dynamics concepts were used to study the nature of these fluctuations. The distribution of eigenvalues was estimated from the conductance fluctuations with Gaussian kernels and it indicates that the carrier motion is chaotic at low temperatures. We argue that a two-phase dynamical fluid model best describes the transport in this system and can be used to explain the violation of the so-called ergodic hypothesis found in graphene.

No MeSH data available.


(a) Optical microscopy image of the sample with indicated current (I) and voltage (V) electrodes. The dotted white line indicates the position of the graphene flake and the light blue regions are the top and bottom h-BN sheets. (b) Schematic of the h-BN encapsulated graphene (BN/G/BN) device (top) and its cross-sectional view (bottom).
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f1: (a) Optical microscopy image of the sample with indicated current (I) and voltage (V) electrodes. The dotted white line indicates the position of the graphene flake and the light blue regions are the top and bottom h-BN sheets. (b) Schematic of the h-BN encapsulated graphene (BN/G/BN) device (top) and its cross-sectional view (bottom).

Mentions: Here, we apply ideas of non-linear dynamics to study the conductance fluctuations in h-BN protected graphene (Fig. 1). First, general properties such as the mobility and the mean free path for this material are obtained from Shubnikov - de Haas oscillations. We then study CF as a function of the back gate voltage and magnetic field to check for ergodic behavior. Furthermore, the power spectra of these fluctuations is calculated and a simple model based on harmonic oscillators is used to estimate the density of defects and compare it to that of a standard graphene sample deposited on a SiO2 substrate.


Conductance fluctuations in high mobility monolayer graphene: Nonergodicity, lack of determinism and chaotic behavior
(a) Optical microscopy image of the sample with indicated current (I) and voltage (V) electrodes. The dotted white line indicates the position of the graphene flake and the light blue regions are the top and bottom h-BN sheets. (b) Schematic of the h-BN encapsulated graphene (BN/G/BN) device (top) and its cross-sectional view (bottom).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016828&req=5

f1: (a) Optical microscopy image of the sample with indicated current (I) and voltage (V) electrodes. The dotted white line indicates the position of the graphene flake and the light blue regions are the top and bottom h-BN sheets. (b) Schematic of the h-BN encapsulated graphene (BN/G/BN) device (top) and its cross-sectional view (bottom).
Mentions: Here, we apply ideas of non-linear dynamics to study the conductance fluctuations in h-BN protected graphene (Fig. 1). First, general properties such as the mobility and the mean free path for this material are obtained from Shubnikov - de Haas oscillations. We then study CF as a function of the back gate voltage and magnetic field to check for ergodic behavior. Furthermore, the power spectra of these fluctuations is calculated and a simple model based on harmonic oscillators is used to estimate the density of defects and compare it to that of a standard graphene sample deposited on a SiO2 substrate.

View Article: PubMed Central - PubMed

ABSTRACT

We have fabricated a high mobility device, composed of a monolayer graphene flake sandwiched between two sheets of hexagonal boron nitride. Conductance fluctuations as functions of a back gate voltage and magnetic field were obtained to check for ergodicity. Non-linear dynamics concepts were used to study the nature of these fluctuations. The distribution of eigenvalues was estimated from the conductance fluctuations with Gaussian kernels and it indicates that the carrier motion is chaotic at low temperatures. We argue that a two-phase dynamical fluid model best describes the transport in this system and can be used to explain the violation of the so-called ergodic hypothesis found in graphene.

No MeSH data available.