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Issue 18, 2017
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Investigation of the metal–insulator transition in NdNiO3 films by site-selective X-ray absorption spectroscopy

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Abstract

In this work, multifunctional oxide NdNiO3 (NNO) thin films grown on a SrTiO3 (STO) substrate using pulsed-laser deposition are studied. Temperature dependent resistivity measurements revealed that NNO/STO samples exhibit a sharp thickness dependent metal–insulator transition (MIT) over a range of 150–200 K. It is known that the electronic properties of correlated oxides are extremely complex and sensitive to changes in orbital occupancy. To evaluate the changes in the electronic and/or crystallographic structure responsible for the MIT, a site-selective (O, Ni and Nd) X-ray absorption near edge structure (XANES) analysis is performed above and below the transition temperature. Analysis of XANES spectra suggests that: (i) in NNO films nominally trivalent Ni ions exhibit multiple valency (bond disproportionation), (ii) intermetallic hybridization plays an important role, (iii) the presence of strong O 2p–O 2p hole correlation at low temperature results in the opening of the p–p gap and (iv) the valency of Nd ions matches well with that of Nd3+. For NNO films exhibiting a sharp MIT, Ni 3d electron localization and concurrent existence of Ni 3d8 and Ni 3d8[L with combining low line]2 states are responsible for the observed transition. At temperatures below the MIT the O 2p–O 2p hole correlation is strong enough to split the O 2p band stabilizing insulating phase. Temperature and thickness dependent differences observed in the site-selective XANES data are discussed in terms of possible mechanisms for the MIT (negative charge-transfer type).

Graphical abstract: Investigation of the metal–insulator transition in NdNiO3 films by site-selective X-ray absorption spectroscopy

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Publication details

The article was received on 03 Feb 2017, accepted on 28 Mar 2017 and first published on 04 Apr 2017


Article type: Paper
DOI: 10.1039/C7NR00742F
Citation: Nanoscale, 2017,9, 6094-6102
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    Investigation of the metal–insulator transition in NdNiO3 films by site-selective X-ray absorption spectroscopy

    N. Palina, L. Wang, S. Dash, X. Yu, M. B. H. Breese, J. Wang and A. Rusydi, Nanoscale, 2017, 9, 6094
    DOI: 10.1039/C7NR00742F

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