single crystal under high pressure up to 40 GPa*

LiOsO₃ is a novel metal that undergoes a second order phase transition from a centrosymetric R-3c structure to a polar R3c structure at T_s=140 K [1]. In this work, we report the measurements of Raman scattering including polarized and unpolarized models on LiOsO₃ single crystal at different pressure up to 40 GPa with a diamond anvil cell. There are four phonon peaks in the phase at ambient condition; new peaks emerge for P > 8.5 GPa. The feature of the high-pressure phase resembles that of LiOsO₃ below T_s at ambient condition [2]. The polar phase appears to be stabilized under high pressure, which is consistent with the observation of dT_s/dP >0 from the resistivity measurement [3]. Results from the symmetry analysis and first-principles calculations will also be presented.