Dispersion relation for (100) and (001)?

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Discussion Overview

The discussion revolves around the differences in the dispersion relations for the (100) and (001) directions in the E-K diagram, specifically in the context of the material InGaAs. Participants explore how these differences may manifest for different types of particles, such as electrons and photons.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions the difference in dispersion relations between the (100) and (001) directions, suggesting that (001) may have lesser dispersion.
  • Another participant requests clarification on the specific system being discussed, indicating that the type of particle (electrons or photons) and the material are crucial for understanding the dispersion relations.
  • A third participant notes that in a cubic system, the dispersion relations for (100) and (001) would be the same due to symmetry, while in a tetragonal system, the dispersion would differ due to the lack of such symmetry.
  • The initial poster acknowledges the need for specificity and asks about the differences in dispersion for photons versus electrons in the context of InGaAs.

Areas of Agreement / Disagreement

Participants generally agree that specificity regarding the system is necessary to make definitive statements about dispersion relations. However, there is no consensus on the implications of the differences between (100) and (001) directions without further details.

Contextual Notes

The discussion highlights the importance of symmetry in determining dispersion relations and indicates that the differences may depend on the material properties and the type of particle involved.

kaikaii
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May I know what is the difference between the dispersion relation for 100 and 001 on the E-K diagram?

Can i say 001 has lesser dispersion? But why is it so?
 
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May be you could be so kind and provide us with some minimal information about what system you are talking. Electrons, photons, some specific material?
 
You can't say anything without having something specific to say it about, as DrDu says. (100) will have the same dispersion as (001) if there is a symmetry that maps the x-axis onto the z axis, like in a cubic system. In a tetragonal system there is no such symmetry so the (100) direction will be different from the (001) direction. And without more specific knowledge about the system in question there is nothing else that can be said.
 
oh yes.. you are right, I'm sorry. may i know what's the difference between the dispersion for photons and electrons? and the material is InGaAs.
 
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