Evidence of multiferroicity inNdMn2O5

Abstract

Recently, $R{\text{Mn}}_{2}{\text{O}}_{5}$ ($R=\text{rare}$ earth, $\text{Bi}, \text{Y}$) type multiferroics have drawn considerable attention, because of magnetically induced ferroelectricity along with an extremely large magnetoelectric coupling. Here, we present a detailed study on ${\text{NdMn}}_{2}{\text{O}}_{5}$ which is a crucial composition between the nonferroelectric ${\text{PrMn}}_{2}{\text{O}}_{5}$ and ferroelectric ${\text{SmMn}}_{2}{\text{O}}_{5}$. We report the results of heat capacity, magnetization, dielectric permittivity, and electric polarization measurements along with an accurate description of the structural and microscopic magnetic properties obtained from high resolution x-ray and neutron diffraction studies. We show that ${\text{NdMn}}_{2}{\text{O}}_{5}$ is ferroelectric, although the magnitude of polarization is much weaker than that of the other multiferroic members. The direction of the polarization is along the crystallographic $b$ axis and its magnitude can be tuned with the application of a magnetic field. Moreover, unlike the other multiferroic members of this series, ferroelectricity in ${\text{NdMn}}_{2}{\text{O}}_{5}$ emerges in an incommensurate magnetic state. The present study also provides evidence in support of the influence of the rare-earth size on the magnetoelectric phase diagram.