Robust Ferroelectric State in Multiferroic Mn${}_{1-x}$Zn${}_x$WO${}_4$

Abstract

We report the remarkably robust ferroelectric state in the multiferroic compound Mn${}_{1-x}$Zn${}_x$WO${}_4$. The substitution of the magnetic Mn${}^{2+}$ with nonmagnetic Zn${}^{2+}$ reduces the magnetic exchange and provides control of the various magnetic and multiferroic states of MnWO${}_4$. Only 5 % of Zn substitution results in a 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 Mn${}_{1-x}$Zn${}_x$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.

6 pages, 8 figures