Modulation of metal-insulator transitions of NdNiO3/LaNiO3/NdNiO3 trilayers via thickness control of the LaNiO3 layer

Abstract

Over the last few decades, manipulating the metal-insulator (MI) transition in perovskite oxides (ABO3) via an external control parameter has been attempted for practical purposes, but with limited success. The substitution of A-site cations is the most widely used technique to tune the MI transition. However, this method introduces unintended disorder, blurring the intrinsic properties. The present study reports the modulation of MI transitions in [10 nm-NdNiO3/t-LaNiO3/10 nm-NdNiO3/SrTiO3 (100)] trilayers (t = 5, 7, 10, and 20 nm) via the control of the LaNiO3 thickness. Upon an increase in the thickness of the LaNiO3 layer, the MI transition temperature undergoes a systematic decrease, demonstrating that bond disproportionation, the MI, and antiferromagnetic transitions are modulated by the LaNiO3 thickness. Because the bandwidth and the MI transition are determined by the Ni-O-Ni bond angle, this unexpected behavior suggests the transfer of the bond angle from the lower layer into the upper. The bond-angle transfer eventually induces a structural change of the orthorhombic structure of the middle LaNiO3 layer to match the structure of the bottom and the top NdNiO3, as evidenced by transmission electron microscopy. This engineering layer sequence opens a novel pathway to the manipulation of the key properties of oxide nickelates, such as the bond disproportionation, the MI transition, and unconventional antiferromagnetism with no impact of disorder.

Unusual Role of Point Defects in Perovskite Nickelate Electrocatalysts

“…Figure a shows the high-resolution X-ray diffraction (XRD) pattern for films treated under various temperatures around the (002) peak of STO. Only the diffractions peaks for STO and NNO were observed on a pristine sample, indicating the formation of single-phase NNO without a polycrystalline phase and impurity . Obviously, the diffraction peak of epitaxial NNO films shifted toward the lower angle (from 47.67 to 47.48°) with the increase of treatment temperature (from 25 to 300 °C), leading to an obvious expansion in the pseudocubic lattice parameter ( a ) of 0.015Å.…”

“…A previous study on the proton doping effect on SmNiO 3 (SNO) has illustrated its capability to trigger colossal variation in conduction behavior, mainly due to the change in Ni electronic states and distortion of NiO 6. 39,40 The XRD pattern indicates the epitaxial growth of the NNO film along the c-axis orientation (2θ LAO at 47.98°and 2θ NNO at 47.47°) 45 since NNO has the pseudocubic lattice constant (a NNO = 3.81 Å), closely matching to that of the LAO substrate (a LAO = 3.789 Å). 46,47 After proton intercalation, the XRD peak apparently shifts to 46.9°, suggesting the expansion of the unit cell partially owing to the occupancy of the proton in the interstitial site of the perovskite unit cell.…”

Electrical transport properties and Kondo effect in La1−xPrxNiO3−δ thin films

“…Bulk 5 and thin film LNO's 7,[9][10][11][12] have been extensively studied, and exhibit various correlation effects which originate with the large Hubbard U and relatively narrow conduction bandwidth 13,14 . In LNO, the nickel ions are considered to be in the Ni 3+ valence state with a d 7 configuration, where d denotes the d orbitals.…”

Study on the decisive factor for metal–insulator transitions in a LaVO3 Mott–Hubbard insulator

“…20 This ambiguity mainly comes from the relatively scarce consideration of the various parameter candidates determining the electrical conduction mechanism compared to other correlated perovskite oxides. 18–23 Inspired by the fact that the B–O–B (B is a 3d metal) tilt angle between the corner shared octahedra in similar Ni and Mn-based perovskites have been reported to control the transport properties by tuning the hopping matrix elements, 22–26 the transport phenomena and its possible origin in undoped and doped lanthanum vanadate along with its structural and optical properties needs to be examined in detail. In this paper, two dopants, Ca 2+ and Sr 2+ of different ionic sizes were substituted in LaVO 3 and the origin of the difference in their transport behaviors is deeply investigated.…”