  A substantial magnetodielectric effect is often an indication of coupled
magnetic and elastic order, such as is found in the multiferroics. However, it
has recently been shown that magnetism is not necessary to produce either a
magnetoresistance or a magnetocapacitance when the material is inhomogeneous
[M. M. Parish and P. B. Littlewood, Phys. Rev. Lett. 101, 166602 (2008)]. Here,
we will investigate the characteristic magnetic-field-dependent dielectric
response of such an inhomogeneous system using exact calculations and numerical
simulations of conductor-dielectric composites. In particular, we will show
that even simple conductor-dielectric layers exhibit a magnetocapacitance, and
thus random bulk inhomogeneities are not a requirement for this effect. Indeed,
this work essentially provides a natural generalisation of the Maxwell-Wagner
effect to finite magnetic field. We will also discuss how this phenomenon has
already been observed experimentally in some materials.
