Correlated Dirac Semimetal State with Highly Mobile Electrons in Perovskite CaIrO₃

The interplay between electron correlation and quantum topology of Dirac electrons have been a subject of great interest. The perovskite AIrO₃ (A=Ca, Sr, Ba) is a candidate of Dirac semimetal with the sufficiently strong correlation on the verge of Mott transition[1]. Although the Dirac band dispersion has been observed by the angle resolved photoemission spectroscopy[2], the quantum transport originating from highly mobile Dirac fermions has been rarely observed in this class of strongly correlated topological semimetals.
In this study, we report the unique quantum transport phenomena of correlated Dirac electrons in perovskite CaIrO₃ with the Mott criticality[3]. We found that the electron mobility exceeds 60,000 cm²/Vs and the giant magnetoresistance emerges in the quantum limit of the Dirac electrons. Combined with ab-initio calculations, we conclude that the interplay between electron correlation and spin-orbit interaction causes the remarkable proximity of Dirac node to the Fermi energy, yielding the highly mobile electrons. In the presentation, the origin of the giant magnetoresistance will also be discussed.
[1] M. Zeb and H. Kee, PRB 86, 085149 (2012)
[2] Y. F. Nie, et al., PRL 114, 016401 (2015)
[3] J. Fujioka, et al., Nat. Commun. 10, 362(2019)