  We have recently reported that the Haldane spin-chain system, Er2BaNiO5,
undergoing antiferromagnetic order below 32 K, is characterized by the onset of
ferroelectricity near 60K due to magnetoelectric coupling induced by
short-range magnetic-order within spin-chains. We have carried out additional
magnetic and dielectric studies to understand the properties well below
antiferromagnetic ordering temperature. We emphasize here on the following: (i)
A strong frequency dependent behaviors of ac magnetic susceptibility and
complex dielectric properties have been observed at much lower temperatures
(below 8 K), that is, reentrant multiglass-like phenomenon, naturally
suggesting the existence of an additional transition well below Neel
temperature; ii) Magnetoelectric phase coexistence is observed at very low
temperature (e.g., T =2K), where the high-field magnetoelectric phase is
partially arrested on returning to zero magnetic field after a cycling through
metamagnetic transition.
