  We have investigated the effects of substituting In for Mn on the
antiferromagnetic phase transition in YMnO3 using magnetic, dielectric, and
specific heat measurements. We prepared a set of isostructural phase pure
hexagonal YMn$_{1-x}$In$_{x}$O$_{3}$ samples having x=0 to x=0.9, which exhibit
a systematic decrease of the antiferromagnetic ordering temperature with
increasing In content. The multiferroic phase, which develops below TN, appears
to be completely suppressed for x$\geq$0.5 in the temperature range
investigated, which can be attributed solely to the dilution of magnetic
interactions as the crystal structure remains hexagonal. Similar to previous
reports, we find an enhancement of the magnetocapacitive coupling on dilution
with non-magnetic ions.
