Materials showing simultaneous ferroelectric and magnetic ordering are attracting a great deal of interest because of their unusual physics and potential applications1. Hemberger et al.2 have reported relaxor-like dielectric properties and colossal magnetocapacitance (in excess of 500%) for the cubic spinel compound CdCr2S4 and related isomorphs3, 4, 5, concluding that CdCr2S4 is a multiferroic relaxor. We argue here, however, that their results might also be explained by a conductive artefact.
