I was wondering if surface electromagnetic waves can propagate at interface between two dielectrics, both isotropic and homogeneous, but having different relative permittivities.
The literature shows that their characteristics must be different.
There are no longer any controversies regarding trapped electromagnetic surface waves along the boundaries in layered materials (as in the case of the Zenneck surface wave, dating from 1907). A detailed overview of the historical and recent developments in the field can be found in [1].
[1] K Li, Electromagnetic Fields in Stratified Media (Springer, Berlin, 2009). https://www.springer.com/us/book/9783540959649