Jahn–Teller distortion in perovskite KCuF3 under high pressure

Single crystals of KCuF3 have been grown by the solution method. We report neutron diffraction under high pressure up to 8 GPa on a powder sample pulverized from KCuF3 crystals. The type-A spin ordering structure found in KCuF3 can be well-explained based on the orbital ordering resolved from this structural study. In comparison with perovskite oxides, the fluoride exhibits a much reduced bulk modulus. Our results also reveal the change of local structural distortion as a function of pressure; the magnitude of Jahn–Teller distortion at ambient condition is dramatically suppressed under high pressure. Extensive comparison of the pressure dependence of the Jahn–Teller perovskite fluoride with that of analogous perovskite oxides has also been made.