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.
Highlights
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
We have studied the effect of the LaNiO3 thickness on the structural and electrical transport properties of NdNiO3/LaNiO3/NdNiO3/SrTiO3(100) trilayer heterostructures with different LaNiO3 thicknesses of 5, 7, 10, and 20 nm and with the bottom and top NdNiO3 thicknesses fixed at 10 nm
The sheet resistance versus the temperature of the trilayers has revealed that the metal-insulator transition temperature TMI decreases as the thickness of the LaNiO3 layer increases with a concomitant decrease of the sheet resistance at 2 K
Summary
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 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. The present study finds that LNO on NdNiO3 (NNO) behaves as bulk NNO while NNO on LNO acts as bulk LNO This fairly surprising result is likely caused by the influence of the lower layer on the oxygen octahedral tilt of the upper layer. Upon increasing the LNO thickness, TMI decreases with concomitant decreases of the residual resistivity This suggests structural coupling between the NNO layers and the middle LNO, which weakens both the MI transition and the bond disproportionation order. Unlike the substitution of RE site ions, this nanoscale approach based on a heterostructure tailors the strength of the bond disproportionation order and the MI and antiferromagnetic transitions, completely excluding the effects of random disorder
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