Low Temperature Structural and Transport Studies of La0.175Pr0.45Ca0.375MnO3

TL;DR

This study investigates the structural and transport properties of La0.175Pr0.45Ca0.375MnO3 down to 2K, revealing a first-order phase transition from orthorhombic to charge-ordered monoclinic structure at 220K, supported by XRD and resistivity data.

Contribution

It provides detailed temperature-dependent structural analysis of LPCMO, identifying a first-order phase transition and charge ordering using XRD and Rietveld refinement.

Findings

LPCMO transitions from orthorhombic to monoclinic phase at 220K.

Charge ordered phase exhibits superlattice peaks in XRD.

Structural transition is of first order with phase coexistence.

Abstract

The temperature (T) dependent x-ray diffraction (XRD) and resistivity measurements of La0.175Pr0.45Ca0.375MnO3 (LPCMO) have been performed down to 2K to understand the structural and transport properties. From room temperature down to 220K, LPCMO exists in orthorhombic phase with Pnma structure and at 220K, it transforms to charge ordered (CO) monoclinic phase with P21/m structure and remains as it is down to 2K. The CO phase is evident from the occurrence of weak but well defined superlattice peaks in the XRD pattern. This structural transformation is of first order in nature as evident from the phase coexistence across the transition region. These results thus clearly illustrate that LPCMO undergoes a first order structural phase transition from charge disordered orthorhombic phase to CO monoclinic phase at 220K, consistent with temperature dependent resistivity results. Our structural analysis of T dependent XRD data using Rietveld refinement infers that below 220K, LPCMO forms commensurate CO monoclinic P21/m structure with four times structural modulation.