Chemical doping-induced flop of ferroelectric polarization in multiferroicMn0.9Co0.1WO4

Abstract

We studied the multiferroic properties of the incommensurate spiral phase of ${\text{Mn}}_{1\ensuremath{-}x}{\text{Co}}_{x}{\text{WO}}_{4}$ using single-crystal neutron-diffraction and ferroelectric measurements. Whereas the rotational plane of the spin spiral is parallel to the $b$ axis for $x\ensuremath{\le}0.05$, it flops by $90\ifmmode^\circ\else\textdegree\fi{}$ for $x=0.10$. As a result, the direction of the ferroelectric polarization also flops from the $b$ to the $a$ axis. These results show that the orientation of the ferroelectric polarization in ${\text{MnWO}}_{4}$ can be controlled via chemical doping.