Strong-correlation induced high-mobility electrons in Dirac semimetal of perovskite oxide

J Fujioka,S Sakai,M Hoshino,R Arita,T Okawa,R Yamada,D Hashizume,Y Tokura,M Kawamura,M Hirayama

doi:10.1038/s41467-018-08149-y

Abstract

Electrons in conventional metals become less mobile under the influence of electron correlation. Contrary to this empirical knowledge, we report here that electrons with the highest mobility ever found in known bulk oxide semiconductors emerge in the strong-correlation regime of the Dirac semimetal of perovskite CaIrO3. The transport measurements reveal that the high mobility exceeding 60,000 cm2V−1s−1 originates from the proximity of the Fermi energy to the Dirac node (ΔE < 10 meV). The calculation based on the density functional theory and the dynamical mean field theory reveals that the energy difference becomes smaller as the system approaches the Mott transition, highlighting a crucial role of correlation effects cooperating with the spin-orbit coupling. The correlation-induced self-tuning of Dirac node enables the quantum limit at a modest magnetic field with a giant magnetoresistance, thus providing an ideal platform to study the novel phenomena of correlated Dirac electron.

Highlights

Electrons in conventional metals become less mobile under the influence of electron correlation
Contrary to this naive expectation, we report here for the strongly correlated Dirac semimetal CaIrO3 that the combination of electron correlation and spin–orbit coupling cooperatively yields highly mobile electrons with the mobility exceeding 60,000 cm[2] V−1 s−1, the largest among the oxide semiconductors, as well as the unique quantum oscillation with giant positive magnetoresistivity ratio of 5500%
For SrIrO3 in the thin film form, the electron pocket with Dirac-like dispersion has been identified by the angle-resolved photoemission spectroscopy, and the Dirac node positions below EF by more than 50 meV17

Summary

Introduction

Electrons in conventional metals become less mobile under the influence of electron correlation. A distinguished feature of Dirac/Weyl electron with massless or small effective mass character is its extremely high mobility, yielding a variety of unusual quantum transports.

Results

Conclusion