Strong charge ordering above room temperature in B-site disordered electron-doped manganite SrMn0.875Mo0.125O3-{\delta}

TL;DR

This study demonstrates the presence of strong charge ordering above room temperature in a B-site disordered electron-doped manganite, revealing phase transitions and complex orbital orderings through diffraction and temperature-dependent measurements.

Contribution

It provides new insights into charge ordering phenomena at high temperatures in disordered manganites, highlighting a transition from charge-ordered to charge-disordered phases.

Findings

Charge ordering occurs at room temperature in SrMn0.875Mo0.125O3-{ extdelta}.

A first-order phase transition at 355K from charge-ordered to charge-disordered phase.

Coexistence of two charge-ordered phases with different orbital orderings.

Abstract

Low as well as high-temperature electron and x-ray diffraction studies have been carried out on a rare-earth free B-site disordered electron-doped manganite SrMn0.875.Mo0.125O3-{\delta} in the temperature range of 83K to 637K. These studies reveal the occurrence of strong charge ordering (CO) at room temperature in a pseudo tetragonally distorted perovskite phase with space-group Pmmm. Non integral modulation vector of 8.95 times along [-110] indicates a charge density wave type modulation. The CO phase with basic perovskite structure Pmmm transforms to a charge disorder cubic phase through a first order phase transition at 355K. Supporting temperature dependent measurements of resistance and magnetization show a metal-insulator and antiferromagnetic transitions across 355K with a wide hysterisis ranging from 150K to 365K. The occurrence of pseudo tetragonality of the basic perovskite lattice with c/a < 1 together with charge-ordered regions with 2-dimensional modulation have been analyzed as the coexistence of two CO phases with 3dx2/3dy2 type and 3dx2-y2 type orbital ordering.