Scattering states at presence of interface with strong SOC

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SUMMARY

The discussion centers on the analysis of scattering states in the presence of a strong spin-orbit coupling (SOC) at an interface. It highlights the distinction between incoming wave functions from the left and right, specifically addressing the absence of certain exponential terms in the wave function representations. The paper asserts that the expressions are valid only when the energy exceeds the potential barrier, with electrons below this threshold not contributing to transport effects. Additionally, the matrix scattering coefficients are defined, emphasizing the role of spin-dependent interactions due to SOC in charge and spin conversion phenomena.

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amjad-sh
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This thread refers to a paper I am working on.
The paper said in the model section that:
In the complete set of scattering states we distinguish two orthogonal set of eigenfunctions:

(i) the states
− →
ϕ incoming from the left, and (ii) the states

←−
ϕ incoming from the right. Away from the interface the wave functions corresponding to the energy ε = (p^2 +k^2 )/2m have:

Capture.PNG
My question is : why the wave functions are represented as a combination of plane waves and why in the terms (z<0) for waves incoming from the left and (z>0) for waves coming from the right there is no e^(ik'z) and e^(-ikz) multiplied by nothing?

then the text completes:
Apparently the expressions of Eq. (3) are only valid when k^2>2mV , that is, when the energy of the scattering states is larger then the height of the interface potential barrier. It can be easily proven that the electrons with k^2<2mV do not contribute to the transport effects we are considering in this work.

In general, the matrix scattering coefficients can be represented as follows:
Capture.PNG

where, ##\sigma_0## is a 2 × 2 unit matrix, and vectors ##\mathbf r,\mathbf r_ 0 ,\mathbf t##,
and ##\mathbf t_0## describe the spin dependent (spin flip) part of the scattering at the interface. A nontrivial spin dependent part of the scattering coefficients, appearing due to the ISOC, is the physical origin of the spin-to-charge and spin-to-spin conversion effects that will be considered in
the next sections.

The text completes:

Capture.PNG


My question: Why the potential barrier is considered smaller than the fermi energy? Is it because we considered the energy of the scattering states bigger than the potential barrier?

@DeathbyGreen Hi sorry I picked you, I wanted to complete the discussion in the previous post https://www.physicsforums.com/threa...rface-between-two-metals.943407/#post-5969726 but I think it may be considered as a new topic.
this is again the paper
 

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both of my questions are so ...:nb)
please ignore this thread:smile:
 

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