Evidence for charge and orbital order in the doped titanates RE_(1-x)Ca_xTiO_3 (RE=Y, Er, Lu)

TL;DR

This study investigates the charge and orbital ordering phenomena in doped titanates RE_(1-x)Ca_xTiO_3, revealing how ionic size influences the insulating phase and its associated charge and orbital arrangements.

Contribution

It provides experimental evidence for charge and orbital order in doped titanates and links these phenomena to the ionic radius of the rare-earth element.

Findings

Insulating phase exhibits charge order with dxy orbital occupation.

Charge and orbital order stabilize the insulating state.

Modulation of Ti-O bonds indicates significant charge modulation.

Abstract

Combining macroscopic and diffraction methods we have studied the electric, magnetic and struc- tural properties of RE_(1-x)Ca_xTiO_3 (RE=Y, Er, Lu) focusing on the concentration range near the metal-insulator transition. The insulating phase, which is stabilized by a smaller rare-earth ionic ra- dius, exhibits charge order with a predominant occupation of the dxy orbital. The charge and orbital ordering explains the broad stability range of the insulating state in RE_(1-x)Ca_xTiO_3 with smaller rare-earth ions. The strong modulation of the Ti-O bond distances indicates sizeable modulation of the electric charge.