Origin of the Non-Linear Pressure Effects in Perovskite Manganites: Buckling of Mn-O-Mn Bonds and Jahn-Teller Distortion of the MnO6 Octahedra Induced by Pressure

TL;DR

This study investigates how pressure influences the electronic and structural properties of La0.85MnO3-d, revealing a transition from bandwidth-driven to Jahn-Teller distortion-driven effects at a critical pressure.

Contribution

It uncovers the pressure-induced transition from bandwidth increase to Jahn-Teller distortions as the main factor affecting TMI in perovskite manganites.

Findings

TMI increases linearly with pressure up to 3.4 GPa

Beyond P*, Jahn-Teller distortions reduce TMI

Bond angles and distances correlate with electronic changes

Abstract

High-pressure resistivity and x-ray diffraction have been measured on La0.85MnO3-d. At low pressures the metal-insulator transition temperature (TMI) increases linearly with pressure up to a critical pressure, P* ~ 3.4 GPa, which is followed by reduction of TMI with increasing pressure. Analysis of the bond distances and bond angles reveal that a bandwidth increase drives the in-crease of TMI for pressure below P*. The reduction of TMI at higher pressures is found to result from Jahn-Teller distortions of the MnO6 octahedra. The role of anharmonic interatomic potential is discussed.