Emerging Magneto-Electric Properties in Orthorhombic Nd$_{1-x}$Y$_{x}$MnO$_{3}$

We have synthesized single crystals of the solid solution Nd$_{1-x}$Y$_{x}$MnO$_{3}$ and we have investigated them using dielectric constant, ferroelectric polarization and single crystal neutron diffraction. We find that with increasing x the A-type magnetic ordering of Mn3+ ions is suppressed and for x $>$ 0.45 a cycloidal magnetic order is found. For these compositions we find an emergent ferroelectric polarization along the c-axis. In the region of 0.35 $<$ x $<$ 0.45 we find a complex co-existence of collinear A-type and incommensurate magnetism. This suggests that the transition from collinear to cycloidal (multiferroic) ground state with x is first order like.