Deriving electrical conduction in 2d crystal

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Discussion Overview

The discussion centers on deriving the conductivity of graphene, specifically seeking a formula that relates current density to various parameters such as electron density, electron velocity, and applied voltage. The scope includes theoretical aspects of electrical conduction in two-dimensional crystals.

Discussion Character

  • Exploratory, Technical explanation, Homework-related

Main Points Raised

  • Remy seeks a specific formula for conductivity in graphene, expressing interest in a relationship involving current density, electron density, and other parameters.
  • One participant suggests considering the Boltzmann semi-classical theory of transport as a potential framework.
  • Another participant notes the complexity of transport theory and recommends exploring an equivalent of the Drude formula for 2D materials, while highlighting the need for a mean free path or time value.
  • Remy acknowledges the complexity and indicates a willingness to attempt the derivation independently.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific formula or approach, and multiple competing views regarding the derivation methods remain present.

Contextual Notes

Participants express uncertainty regarding the applicability of traditional models like the Drude formula to graphene and the challenges in computing necessary parameters such as mean free path or time.

steenreem
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Hey.

I want to derive the conductivity of graphene.
I'm looking for a formula of the sort:

J = \frac{e}{\hbar} n \frac{dE}{dk} D(E) \Delta E
where
\frac{1}{\hbar} \frac{dE}{dk}
is the electron velocity,
D(E) = \frac{dN}{dE}
is the density of states,
\Delta E
might be the applied voltage.
n
is the free electron density,
J
is the current density and
e is the electron charge.

Thanks,
Remy.
 
Last edited:
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Have you looked at the Boltzmann semi-classical theory of transport?
 
Well I just did but it's a but too much for me. I just want a simple formula for 2D crystals like graphene.
 
Well, transport is a difficult topic. You could try working out the equivalent of the Drude formula for 2D, which shouldn't be hard, but you are going to need a value for the mean free path or time, which is not trivial to compute. And it may not work well for graphene.
 
Okay thanks. I'll try working it out on my own now.
 

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