Hi
I want to enter the conductivity of superconductor in cst but according to this paper, it is complex and depend on the angular frequency of incident terahertz wave. how can I do it?
thanks for your help
Conductivity of a superconductor is a complex quantity which can be described by two fluid model. The imaginary part of the complex conductivity is responsible
for unique superconducting properties of such material (supercurrent) . Formally it is equivalent to a negative permittivity. The imaginary part of conductivity is
frequency dependent and at THz frequencies would become very small. This is
the main reason why superconductors are not used in this frequency range.
More details about the complex coductivity of YBCO at microwave frequencies
can be found in the following bublication: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 23, NO. 2, 1501011, 2013
Thanks Dr Jerzy Antoni for your answer.
According to your answer I can neglect the imaginary part of conductivity?
And because the real part is described by Drude model, I can use this model in cst for superconducting ?
It depends on frequency. Note that at 13 GHz the imaginary part of
conductivity of YBCO is about 10^8 S/m while the real part is two orders of
magnitude smaller. At 1.3 THz the real and the imaginary part of conductivity
will be similar (the imaginary part vary with frequency as f^-(1), while the real part
can be consider as a constant value).
Also when you use Drude model for the real part of conductivity it is necessary
to know plasma frequency for YBCO.
Thanks but I'm working on NbN at THz. So I dont know what to do for its conductivity.
Note that you can find in literature the surface resistance and the London
penetration depth for NbN films from which you can evaluate the complex
conductivity of this material in the same way as for YBCO.
Surface resistance: Physica C 378–381 (2002) 1295–1300
London penetration depth: Applied Physics Letters 68(4):562 - 563
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