Insulator-metal transition in deep Sr-vacant spin-orbit Mott insulator Sr2IrO4

TL;DR

This study investigates how deep Sr-vacancies in Sr2IrO4 induce an insulator-metal transition, structural changes, and magnetic property alterations, revealing the critical role of lattice distortions and spin-orbit interactions.

Contribution

It demonstrates that deep Sr-vacancies cause a structural transition and induce an insulator-metal transition in Sr2IrO4, highlighting the interplay between lattice structure and electronic states.

Findings

Insulator-metal transition occurs at x > 0.48 in Sr2-xIrO4.

Significant structural changes accompany the transition, including lattice constant and bond length modifications.

Magnetic properties such as T0 and TN show abrupt drops near the transition point.

Abstract

Sr2IrO4 exhibits a novel insulating state assisted by spin-orbit interactions. A series of polycrystalline samples of Sr2-xIrO4 have been synthesized. It is found that deep Sr-vacancies of Sr2-xIrO4 greatly reduce the rotation of IrO6 octahedral, and more importantly, a significant structural change occurs around x = 0.48 in both the lattice constants and the Ir-O2 bond length. An insulator-metal transition (IMT) appears and a non-Fermi-liquid metallic electronic state has been proved at x>0.48 in Sr2-xIrO4. Furthermore, a sudden drop emerges of the localization temperature T0 and the antiferromagnetic (AFM) transition temperature TN in Sr1.5IrO4, together with the Curie-Weiss temperature reversing its sign. These abrupt changes are closely related with the reduction of the rotation crystal structure.