Electron-doped Sr2IrO4-δ (0≤δ≤0.04): Evolution of a disordered Jeff=1/2 Mott insulator into an exotic metallic state

Stoichiometric Sr2IrO4 is a ferromagnetic J(eff)=1/2 Mott insulator driven by strong spin-orbit coupling. Introduction of very dilute oxygen vacancies into single-crystal Sr2IrO4-delta with delta <= 0.04 leads to significant changes in lattice parameters and an insulator-to-metal transition at T-MI=105 K. The highly anisotropic electrical resistivity of the low-temperature metallic state for delta approximate to 0.04 exhibits anomalous properties characterized by non-Ohmic behavior and an abrupt current-induced transition in the resistivity at T*=52 K, which separates two regimes of resistive switching in the nonlinear I-V characteristics. The novel behavior illustrates an exotic ground state and constitutes a new paradigm for devices structures in which electrical resistivity is manipulated via low-level current densities similar to 10 mA/cm(2) (compared to higher spin-torque currents similar to 10(7)-10(8) A/cm(2)) or magnetic inductions similar to 0.1-1.0 T.