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

Abstract

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.

Electron Doping-Induced Metal–Insulator Transition in LaNiO3 and Memory Devices

“…Epitaxial nickelate thin films are usually deposited on LaAlO 3 (LAO) substrates by physical vapor deposition. Some recent studies on chemical solution deposition (CSD) of epitaxial nickelate thin films have been reported, with comparable crystallinity and sharp MIT features. − CSD, as a non-vacuum deposition method, is suited to control the ratio of rare-earth elements and Ni by adjusting the weight of the solid precursors. ,,− LaNiO 3 (LNO) is the only member of the rare-earth nickelates that is metallic at all temperatures as it retains the rhombohedral lattice structure which maintains an efficient Ni–O–Ni orbital overlap for metallic conductance even at low temperatures. , A lot of effort has been devoted to obtaining thermally driven MIT in LNO, such as ultra-thin films with the thickness of a few unit cells, construction of superlattices, interface, orientation, or oxygen deficiency effects. − Here, we demonstrate that LNO can be electron-doped into an insulator with dramatic conductivity suppression regardless of the temperature. The LNO thin films were deposited by the CSD method and were systematically characterized to confirm the film quality.…”

Tunable and enhanced Rashba spin-orbit coupling in iridate-manganite heterostructures

“…The interaction of transition metal oxides with SrIrO 3 exhibited very interesting properties, for example, tuning magnetic anisotropy in La 1−x Sr x MnO 3 /SrIrO 3 superlattices through octahedral rotation [24,25] and inducing metal-insulator transition in LaNiO 3 by charge transfer from SrIrO 3 [26]. Novel magnetic phases such as spin-glass and skyrmions in SrRuO 3 /SrIrO 3 superlattices were also reported [27].…”

Study of Electronic States in LaNiO3/SrRuO3 Bilayers: Interface‐Induced Magnetism and Charge Transfer

“…Thus, the magnetic response of LNO triggered the electron transport between LNO and SrIrO 3 (SIO) layers to exhibit the low-temperature metal-to-insulator transition in LNO/SIO heterostructure. [18] From all the results of aforementioned studies, any change in the electronic structure in a heterostructure significantly amplifies the charge transfer across the interface and changes their magnetic properties. Though interface-induced changes in physical properties have been reported for different combinations of 3d and 4d transition metal oxide heterostructures, the underlying phenomena such as strain-induced magnetism and modification of concentration of electronic states in the oxide heterostructure still have to be understood for engineered interfaces.…”

“…Thus, the magnetic response of LNO triggered the electron transport between LNO and SrIrO 3 (SIO) layers to exhibit the low‐temperature metal‐to‐insulator transition in LNO/SIO heterostructure. [ 18 ]…”