Continuous first order orbital order-disorder transition in Nd1-xCaxMnO3

TL;DR

This study investigates the orbital order-disorder transition in Nd1-xCaxMnO3, revealing a continuous first-order transition with phase coexistence at low doping, which diminishes as doping increases, using high-temperature X-ray diffraction.

Contribution

It provides new insights into the nature of the orbital transition in Nd1-xCaxMnO3, highlighting the continuous aspect of the first-order transition and doping effects.

Findings

Phase coexistence over a broad temperature range at low doping

Transition resembles a martensitic transformation

Doping suppresses phase coexistence and the first-order transition

Abstract

The nature of the cooperative Jahn-Teller (JT) transition accompanied by orbital order-disorder in Nd1-xCaxMnO3 has been studied by high temperature (300 - 1200K) synchrotron and laboratory X-ray powder diffraction in the low doping region (0<x<0.1). For very low doping a large temperature range of phase coexistence associated with a first-order transition has been observed, resembling a martensitic transformation. The transition appears continuous because of a gradual evolution of the volume fractions of the phases over a broad temperature interval. The first-order nature of the transition and the phase coexistence is suppressed with increasing of doping.