Physical requirements on material parameters Print E-mail

We think that introducing effective electromagnetic parameters we should start from quite general considerations, which need to be discussed and agreed.

In our opinion, from the most general point of view, the following fundamental requirements for physically sound effective material parameters of all linear passive media in thermodynamically equilibrium states should hold:

Physically sound (local) material parameters

  • are independent of the spatial distribution of fields excited in the material sample,
  • are independent of the geometrical size and shape of the sample,
  • satisfy the causality requirement (Kramers-Kronig relations),
  • satisfy the passivity requirement (II law of thermodynamics).

The first two requirements are difficult to satisfy for many nano-structured samples, mainly because the samples usually contain only a few (or even one) layers of inclusions across their thickness. This introduces limitations on the applicability area of the effective parameters.The last two basic physical requirements must be satisfied to ensure that the use of the effective medium description does not lead to nonphysical results.

There can be different opinions on this issue, and we think it is important that the research community has a coherent view on this starting point. If you feel that there is a need for discussion, please let us know: we can set up a forum at this site.