Metal–Insulator Transition of LaNiO3 Films in LaNiO3/SrIrO3 Heterostructures

LaNiO3/SrIrO3 (LNO/SIO) heterostructures were deposited epitaxially on (001) SrTiO3 substrates. Transport characteristics of these LNO/SIO heterostructures were investigated as functions of LNO and SIO thickness. It has been observed that interfacing with SIO induces a metal–insulator transition at about 20 K in a 10 unit cell thick LNO film, which is otherwise metallic down to 2 K. In addition, this metal–insulator transition is irrelevant to the thickness of SIO, indicative of an interfacial effect. X-ray absorption measurements reveal an electron transfer from LNO to SIO across the interface. Meanwhile, the observation of a spin-glass-like state manifests the importance of spin-dependent scattering. The metal–insulator transition is discussed in terms of Kondo effect by random scattering from impurity spins associated with the interfacial electron transfer and the Dzyaloshinskii–Moriya interaction due to strong spin–orbit coupling inherent in 5d perovskite SIO