Magnetic and dielectric behavior of the spin-chain compound Er2BaNiO5 well below its Néel temperature

We have recently reported that the Haldane spin-chain system, Er2BaNiO5, undergoing antiferromagnetic order below (TN=) 32 K, is characterized by the onset of ferroelectricity near 60 K 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 TN. 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 (<8 K), that is, "reentrant multiglass-like" phenomenon, naturally suggesting the existence of an additional transition well below TN. (ii) "Magnetoelectric phase coexistence" is observed at very low temperature (e.g., T = 2 K), where the high-field magnetoelectric phase is partially arrested on returning to zero magnetic field after a cycling through metamagnetic transition.