Pressure-induced enhancement of non-polar to polar transition temperature in metallic LiOsO3

LiOsO3 undergoes a continuous transition from a centrosymmetric R 3 ¯ c structure to a polar R3c structure at Ts = 140 K. By combining transport measurements and first-principles calculations, we find that Ts is enhanced by applied pressures, and it reaches a value of ∼250 K at ∼6.5 GPa. The enhancement is due to the fact that the polar R3c structure of LiOsO3 has a smaller volume than the centrosymmetric R 3 ¯ c structure. Pressure generically favors the structure with the smallest volume, and therefore further stabilizes the polar R3c structure over the R 3 ¯ c structure, leading to the increase in Ts.