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Free keywords:
LaMnO3; high pressure; phase transition; Jan-Teller effect; insulator-metal-transition; X-ray diffraction
Abstract:
Structural, vibrational and electronic properties of LaMnO3 under pressures up to 38 GPa have been studied by synchrotron X-ray powder diffraction, Raman spectroscopy, optical reflectivity, and transport measurements. The cooperative Jahn- Teller distortion of the MnO6 octahedra of the perovskite-type structure is continuously suppressed with increasing pressure, a process which appears completed at similar to20 GPa. The system remains insulating to 32 GPa, where an insulator-metal transition is observed. This transition is attributed to strengthened Mn-O-Mn interactions due to the increasing overlap of atomic orbitals.