We have studied multiferroic ${\mathrm{YMn}}_2{\mathrm{O}}_5$ by high-pressure neutron diffraction in a large pressure range from 0.5 to 6.3 GPa. We observe a pressure-induced commensurate (PCM) phase with a propagation vector $\left(\frac{1}{2}0\frac{1}{2}\right)$ that is different from those observed at ambient pressure. It coexists with the ambient pressure phases up to the highest pressure, with an increased contribution as the pressure increases. The PCM phase, which is likely generic in the $R{\mathrm{Mn}}_2{\mathrm{O}}_5$ family, should be taken into account to understand the strong variation of the electric polarization under pressure.

• Received 10 June 2015

DOI:https://doi.org/10.1103/PhysRevB.92.060410