Members of CEARL have shown that a properly designed EBG can have surface impedance equivalent to that of a thin magnetic substrate backed by a PEC ground plane. We call such an artificial ferrite material a meta-ferrite.
The Synthesis of Metamaterial Ferrites for RF Applications Using Electromagnetic Bandgap Structures - More Info
Metaferrites: Using Electromagnetic Bandgap Structures to Synthesize Metamaterial Ferrites
Matched Impedance Thin Planar Composite Magneto-Dielectric Metasurfaces