High Pressure Study on the Multiferroic State in Mn$_{1-x}$Co$_x$WO$_4$: x = 0.135 and x = 0.15

Mn$_{1-x}$Co$_x$WO$_4$ has an interesting and complex phase diagram where 2 multiferroic phases coexist at x = 0.15. For x $<$ 0.15 a spiral spin structure forms, while in contrast a conical spin is observed for x $>$ 0.15. High pressure polarization measurements on x = 0.135 observed a polarization flop and an increase in the polarization, indicating the a-c spiral is converted to the conical spin. An enhancement of the polarization by $\sim$ 400\% is seen for x = 0.15, at the highest pressure measured. High pressure neutron measurements found supporting results.