Pressure-induced polarization reversal in multiferroic YMn2O5

The low-temperature ferroelectric polarization of multiferroic YMn2O5 is completely reversed at a critical pressure of 10 kbar and the phase transition from the incommensurate to the commensurate magnetic phase is induced by pressures above 14 kbar. The high-pressure data correlate with thermal-expansion measurements, indicating a significant lattice strain at the low-temperature transition into the incommensurate phase. The results support the exchange striction model for the ferroelectricity in multiferroic RMn2O5 compounds and they show the importance of magnetic frustration as well as the spin-lattice coupling.