MIrO3 (M= Na, Ca, Sr, and Ba) compounds are important systems of oxide iridates. Since Ir is a 5d element, the metallic ground states can be expected, but MIrO3 are found to be Mott insulators or semimetals [1-3]. NaIrO3 has an orthorhombic post-perovskite structure of typical ABO3 with the space group Cmcm, itand is a Mott insulator [4]. CaIrO3, with space group Pbnm, is a perovskite, which is a paramagnetic semimetal [5], and BaIrO3 is a weak ferromagnetic semiconductor [6]. Compared with 3d and 4d elements, the 5d ones are spatially more prolonged, which lead to smaller on-site Coulomb repulsive interaction. Mott physics has been the foundation for understanding numerous intriguing physical properties of strongly correlated electron systems.
In the series of Ruddlesen-Proper, one family of iridates of Srn+1IrnO3n+1, Sr2IrO4 (n=1) and Sr3Ir2O7 (n=2), are an antiferromagnetic Jeff = 1/2 Mott insulator and barely an insulator, respectively [7-16], and SrIrO3 for n = ∞ is a paramagnetic semimetal [17, 18]. Sr2IrO4 and Sr3Ir2O7 have been thoroughly studied [19]. To obtain a complete picture of Mott metal-insulator transition (MIT), it is essential to analyze the low energy electronic structure of SrIrO3. Moreover, theories based on tightthe tight bonding model have suggested that SrIrO3 is an exotic semimetal [19], induced by the delicate interplay between the spin orbit interaction (SOI) and electron correlations.
Ahsen et al. [20] investigated the overall phase diagram of the SrIrO3 compound (space group Pbnm) for U vs SOC, theyand found that this compound has three phases, nonmagnetic metal/semimetal, magnetic metal, and magnetic insulator. Z. T. Liu andet al. [19] have studied the low-lying electronic band structure of the perovskite structured SrIrO3 film by applying the combo of OMBE and in-situ ARPES,; they have shown that the electron-like bands around U and the hole-like bands around R cross the Fermi level simultaneously, giving the direct evidence of the semimetallic ground state in the orthorhombic perovskite SrIrO3.