Field-induced multiple metal-insulator crossovers of correlated Dirac electrons of perovskite CaIrO$_3$

TL;DR

This study reveals that correlated Dirac electrons in perovskite CaIrO$_3$ undergo multiple field-induced metal-insulator crossovers, driven by electron correlation and external magnetic fields, resulting in giant magnetoresistance.

Contribution

It demonstrates for the first time the field-induced multiple metal-insulator crossovers in correlated topological Dirac semimetals, highlighting the interplay of electron correlation and magnetic field effects.

Findings

Observation of successive metal-insulator-metal crossovers under magnetic field.

Giant magnetoresistance ratio of 3,500% at 18 T and 1.4 K.

Insulating state linked to charge/spin density wave ordering.

Abstract

The interplay between electron correlation and topology of relativistic electrons may lead to a new stage of the research on quantum materials and emergent functions. The emergence of various collective electronic orderings/liquids, which are tunable by external stimuli, is a remarkable feature of correlated electron systems, but has rarely been realized in the topological semimetals with high-mobility relativistic electrons. Here, we report that the correlated Dirac electrons with the Mott criticality in perovskite CaIrO$_3$ show unconventional field-induced successive metal-insulator-metal crossovers in the quantum limit accompanying a giant magnetoresistance (MR) with MR ratio of 3,500 % (18 T and 1.4 K). The analysis shows that the insulating state originates from the collective electronic ordering such as charge/spin density wave promoted by electron correlation, whereas it turns into the quasi-one-dimensional metal at higher fields due to the field-induced reduction of chemical potential, highlighting the highly field-sensitive character of correlated Dirac electrons.