Continuous Transition between Antiferromagnetic Insulator and Paramagnetic Metal in the Pyrochlore Iridate Eu2Ir2O7

TL;DR

This study investigates the continuous phase transition in Eu2Ir2O7 from a paramagnetic metal to an antiferromagnetic insulator, highlighting the roles of magnetic order, electronic correlation, and spin-orbit coupling.

Contribution

It provides detailed experimental evidence of a continuous transition and emphasizes the importance of magnetic order in gap formation in pyrochlore iridates.

Findings

Transition is continuous within ~1% stoichiometry variation.

Insulating phase is close to an antiferromagnetic semimetal.

Magnetic order is crucial for charge gap opening.

Abstract

Our single crystal study of the magneto-thermal and transport properties of the pyrochlore iridate Eu2Ir2O7 reveals a continuous phase transition from a paramagnetic metal to an antiferromagnetic insulator for a sample with stoichiometry within ~1% resolution. The insulating phase has strong proximity to an antiferromagnetic semimetal, which is stabilized by several % level of the off-stoichiometry. Our observations suggest that in addition to electronic correlation and spin-orbit coupling the magnetic order is essential for opening the charge gap.