  The Haldane spin-chain (S=1) insulating compound, Sm2BaNiO5, which has been
proposed to order antiferromagnetically around (T_N=) 55 K, was investigated
for its complex dielectric permittivity, magnetodielectric and pyrocurrent
behavior as a function of temperature (T). In order to enable meaningful
discussions, the results of ac and dc magnetizatioin and heat-capacity studies
are also reported. We emphasize on the following findings: (i) There is a
pyrocurrent peak near T_N, but it is shown not to arise from ferroelectricity,
but possibly due to 'thermally stimulated depolarization current', unlike in
many other members of this rare-earth series, in which case ferroelectric
features were reported at or above T_N; (ii) however, the pyrocurrent measured
in the presence of a bias electric field (after cooling in zero electric field)
as well as dielectric constant reveal a weak peak with increasing T around 22 K
- the temperature around which population of the exchange-split excited state
of Kramers doublet has been known to occur. This finding suggests that this
compound presents a novel situation in which multiferroicity is induced by an
interplay between crystal-field effects and exchange interaction. No multiglass
features could be observed down to 2 K unlike in many members of this family.
