  Muon spin relaxation measurements are reported on samples of dimethylammonium
metal formates containing magnetic divalent nickel, cobalt, manganese, and
copper ions. These hybrid organic-inorganic perovskites exhibit weak
ferromagnetism and are, apart from the copper system, multiferroics with well
separated magnetic and antiferroelectric transitions. We use muons to follow
the sublattice magnetization, observing the effect of the spin reorientation
transitions below TN and the criticality approaching TN. The multiferroic
samples have three-dimensional antiferromagnetic interactions, but the copper
sample shows quasi-one-dimensional behavior due to its Jahn-Teller distorted
structure, with a ratio of its inter- and intrachain exchange constants
j/J=0.037.
