  By combining dielectric, specific heat, and magnetization measurements and
high-resolution neutron powder diffraction, we have investigated the
thermodynamic and magnetic/structural properties of the metastable orthorhombic
perovskite ErMnO_3 prepared by high-pressure synthesis. The system becomes
antiferromagnetically correlated below 42 K and undergoes a lock-in transition
at 28 K with propagation wave vector (0,k_b,0), which remains incommensurate at
low temperature. The intercorrelation between the magnetic structure and
electric properties and the role of the rare earth moment are discussed.
