A new surface effect exhibited by the ferroelectric YMnO 3

Abstract
It is shown that on 001 surface of as-grown monocrystalline YMnO3 c platelets there exists a ferroelectric layer which has a c parameter slightly different from that of the bulk and which contains a large amount of bismuth coming from the growth flux.Some properties of this layer are investigated using 'ferroelectric X-ray anomalous scattering effect' and pyroelectric effect.Consequences of these results are discussed.