Spin-orbit-controlled metal-insulator transition in metastable SrIrO3 stabilized by physical and chemical pressures

Spin-orbit coupling (SOC) plays a vital role in determining the ground state and forming novel electronic states of matter where heavy elements are involved. Here, the prototypical perovskite iridate oxide SrIrO3 is investigated to gain more insights into the SOC effect in the modification of electronic structure and corresponding magnetic and electrical properties. The high pressure metastable orthorhombic SrIrO3 is successfully stabilized by physical and chemical pressures, in which the chemical pressure is induced by Ru doping in Ir site and Mg substitution of Sr position. Detailed structural, magnetic, electrical characterizations and density functional theory (DFT) calculations reveal that the substitution of Ru for Ir renders an enhanced metallic characteristic, while the introduction of Mg into Sr site results in an insulating state with 10.1% negative magnetoresistance at 10 K under 7 T. Theoretical calculations indicate that Ru doping can weaken the SOC effect, leading to the decrease of orbital energy difference between J1/2 and J3/2, which is favorable for electron transport. On the contrary, Mg doping can enhance the SOC effect, inducing a metal-insulator-transition (MIT). The electronic phase transition is further revealed by DFT calculations, confirming that the strong SOC and electron-electron interactions can lead to the emergence of insulating state. These findings underline the intricate correlations between lattice degrees of freedom and SOC in determining the ground state, which effectively stimulate the physical pressure between like structures by chemical compression.