Pressure-temperature phase diagram of multiferroic EuTiO3

The structural transformation of multiferroic EuTiO₃ has been intensively investigated by synchrotron x-ray diffraction at pressures up to 50.3 GPa and temperatures from 50 to 500 K. A pressure-induced antiferrodistortive phase transition from cubic P m 3 ¯m to tetragonal I 4 /m c m space group has been observed, identical to the one that has been previously explored at ambient pressure and low temperatures. Several compression/decompression cycles at different temperatures have been carried out to accurately map the transition, and as a result a P -T phase diagram for EuTiO₃ has been constructed. The observed phase transition exhibits a positive d P_c/d T (P_c being the critical pressure of the transition) and has many similarities with isostructural SrTiO₃, although the absence of magnetoelectric interactions in the latter accounts for the different phase boundaries between the two materials.