Pressure effects on magnetic ground states in cobalt-doped multiferroic Mn1-xCoxWO4

Using ambient pressure x-ray and high pressure neutron diffraction, we studied the pressure effect on structural and magnetic properties of multiferroic Mn1-xCoxWO4 single crystals (x=0, 0.05, 0.135, and 0.17) and compared it with the effects of doping. Both Co doping and pressure stretch the Mn-Mn chain along the c direction. At high doping level (x=0.135 and 0.17), pressure and Co doping drive the system in a similar way and induce a spin-flop transition for the x=0.135 compound. In contrast, magnetic ground states at lower doping level (x=0 and 0.05) are robust against pressure but experience a pronounced change upon Co substitution. As Co introduces both chemical pressure and magnetic anisotropy into the frustrated magnetic system, our results suggest the magnetic anisotropy is the main driving force for the Co induced phase transitions at low doping level, and chemical pressure plays a more significant role at higher Co concentrations.