We report on the remarkably robust ferroelectric state in the multiferroic compound ${\mathrm{Mn}}_{1-x}{\mathrm{Zn}}_x{\mathrm{WO}}_4$. Substitution of the magnetic ${\mathrm{Mn}}^{2+}$ with nonmagnetic Zn${}^{2+}$ reduces the magnetic exchange and provides control of the various magnetic and multiferroic states of ${\mathrm{MnWO}}_4$. Only $5\%$ of Zn substitution results in complete suppression of the frustrated collinear (paraelectric) low-temperature phase. The helical magnetic and ferroelectric phase develops as the ground state. The multiferroic state is stable up to a high level of substitution of more than $50\%$. The magnetic, thermodynamic, and dielectric properties, as well as the ferroelectric polarization of single crystals of ${\mathrm{Mn}}_{1-x}{\mathrm{Zn}}_x{\mathrm{WO}}_4$, are studied for different substitutions up to $x=0.5$. The magnetic phases have been identified in single-crystal neutron-scattering experiments. The ferroelectric polarization scales with the neutron intensity of the incommensurate peak of the helical phase.

• Received 29 October 2010

DOI:https://doi.org/10.1103/PhysRevB.83.014401