Probing the metal-insulator transition in Ni(III)-oxide perovskites

Zhou, Jianshi; Goodenough, John B.; Dąbrowski, B.; Klamut, P. W.; Bukowski, Z.

doi:10.1103/physrevb.61.4401

Cited by 72 publications

(93 citation statements)

References 18 publications

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“…1 10 K. As seen, in analogy to the bulk LNO, the n = 10 SL exhibits a highly metallic behavior ascribed to the three dimensional regime. On the other hand, unlike the bulk which is known to follow a T 2 Fermi liquid behavior at low temperatures [18], the low-temperature resistivity ρ at n = 10 shows a peculiar ∝ T 3/2 dependence below 200 K (see Fig. 1(b)).…”

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confidence: 97%

Quantum confinement of Mott electrons in ultrathin LaNiO3/LaAlO3superlattices

et al. 2011

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We investigate the electronic reconstruction in (LaNiO3)n/(LaAlO3)3 (n =3, 5 and 10) superlattices due to the quantum confinement (QC) by d.c. transport and resonant soft x-ray absorption spectroscopy. In proximity to the QC limit, a Mott-type transition from an itinerant electron behavior to a localized state is observed. The system exhibits tendency towards charge-order during the transition. ab initio cluster calculations are in good agreement with the absorption spectra, indicating that the apical ligand hole density is highly suppressed resulting in a strong modification of the electronic structure. At the dimensional crossover cellular dynamicalmean-field calculations support the emergence of a Mott insulator ground state in the heterostructured ultra-thin slab of LaNiO3. PACS numbers:Prompted by the discovery of high-T c superconductivity in cuprate compounds there has been a surge of activity to discover materials with even higher transition temperature [1]. Recent remarkable advances in synthesis of artificial layers of complex oxides along with the progress in computational methods have re-energized the search for novel superconductors outside of the cuprate family [2,3].Towards the challenge, a recent proposal has been put forward to use heterostructuring and orbital engineering to turn hole-doped alternating unit-cell thin layers of a correlated metal LaNiO 3 (LNO) and band-gap dielectric LaAlO 3 (LAO) [4]. The proposal utilizes the Ni III 3d 7 low-spin state in the bulk with a single unpaired electron occupying the degenerate (d x 2 −y 2 /d 3z 2 −r 2 ) e g orbital whose nodes point to the planar and apical ligands of the octahedra, respectively. Both t-J and LDA+DMFT calculations [4,5] suggest that the quantum confinement together with the electronic correlations should make it possible to localize or empty the d 3z 2 −r 2 band leaving the conduction electron in the d x 2 −y 2 band. Epitaxial strain is also suggested as a mean of the orbital control to manipulate the d 3z 2 −r 2 orbital to appear above d x 2 −y 2 and play the analogous role of the axial orbital of the high-T c cuprates.Despite the attractive simplicity of the structure, the experimental realization of LNO/LAO superlattice (SL) presents a large degree of ambiguity in selecting a specific electronic ground state caused by (i) the intrinsic propensity of orthonickelates to charge-ordering [6,7], (ii) the orbital polarization due to chemical confinement imposed by interfacial bonding [8,9], (iii) polar discontinuity [10,11], (iv) epitaxial constraint on the crystal symmetry [12,13] and (v) quantum confinement [14,15]. Even for the undoped LNO/LAO SL (i.e. the proposed parent cuprate-like compound), the synergetic action of these phenomena will likely render the theoretical problem intractable to a priori predict whether the cuprate-like physics can be experimentally realized.Here we report on emergence of a Mott-type metalinsulator transition (MIT) at the dimensional crossover in the experimentally realized (LNO) n /(LAO) 3 SLs. By usin...

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confidence: 97%

Quantum confinement of Mott electrons in ultrathin LaNiO3/LaAlO3superlattices

et al. 2011

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“…Thermal hysteresis has also been observed in direct current resistivity when T N is nearby or coincide with T MI , for example, Re ¼ Pr and Nd (ref. 35). As T N ( T MI , reported resistivity data showed that the hysteretic behaviour is highly suppressed or absent [36][37][38] .…”

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confidence: 99%

Heterointerface engineered electronic and magnetic phases of NdNiO3 thin films

et al. 2013

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Mott physics is characterized by an interaction-driven metal-to-insulator transition in a partially filled band. In the resulting insulating state, antiferromagnetic orders of the local moments typically develop, but in rare situations no long-range magnetic order appears, even at zero temperature, rendering the system a quantum spin liquid. A fundamental and technologically critical question is whether one can tune the underlying energetic landscape to control both metal-to-insulator and Néel transitions, and even stabilize latent metastable phases, ideally on a platform suitable for applications. Here we demonstrate how to achieve this in ultrathin films of NdNiO 3 with various degrees of lattice mismatch, and report on the quantum critical behaviours not reported in the bulk by transport measurements and resonant X-ray spectroscopy/scattering. In particular, on the decay of the antiferromagnetic Mott insulating state into a non-Fermi liquid, we find evidence of a quantum metal-to-insulator transition that spans a non-magnetic insulating phase.

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“…Nonequivalent Ni sites coexist even at the metallic state 11,12 and are compatible with a segregation into two phases, where a more localized electron phase is embedded in a conducting background 23 . The M I transition takes place with the increase of the less hybridized phase related to the other.…”

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Spin-orbit-induced mixed-spin ground state inRNiO3perovskites probed by x-ray absorption spectroscopy: Insight into the metal-to-insulator transition

et al. 2005

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We report on a Ni L2,3 edges x-ray absorption spectroscopy (XAS) study in RNiO3 perovskites. These compounds exhibit a metal to insulator (M I) transition as temperature decreases. The L3 edge presents a clear splitting in the insulating state, associated to a less hybridized ground state. Using charge transfer multiplet calculations, we establish the importance of the crystal field and 3d spin-orbit coupling to create a mixed-spin ground state. We explain the M I transition in RNiO3 perovskites in terms of modifications in the Ni 3+ crystal field splitting that induces a spin transition from an essentially low-spin (LS) to a mixed-spin state.PACS numbers: 61.10. Ht, 71.30.+h, 75.10.Dg, 75.25.+z Keywords: x-ray absorption spectroscopy, XAS, metal-insulator transition, charge transfer multiplet theory Rare-earth nickel perovskites (RNiO 3 , R=rare earth) present a sharp well-defined metal to insulator (M I) transition as temperature decreases 1 . The transition temperature, T MI , increases with reducing the R ion size, which determines the degree of distortion of the structure 2 . It was proposed that the gap opening would be due to a smaller Ni-O-Ni superexchange angle leading to a reduction of the bandwidth 3 . However, nonnegligible electron-phonon interactions 4 and a shift in T MI with oxygen isotope substitution 5 evidenced the importance of modifications in Ni-O interatomic distances, suggesting a phonon assisted mechanism for conduction. As temperature decreases, these nickelates undergo a magnetic transition to an unusual antiferromagnetic order 6,7,8 . The magnetic arrangement for the lighter R compounds (R=Pr, Nd, Sm, Eu) was refined with a single Ni moment (0.9µ B ) and required non-equivalent couplings among Ni ions to stabilize the structure 6,7 . This is a quite unusual situation in an orthorhombic crystallographic structure whose Ni sites are all equivalent 2 . For the heavier R compounds, Alonso et al.8,9 established a monoclinic distortion in the crystallographic structure leading to two different Ni sites with longer and shorter Ni-O distances alternating along the three axis. The antiferromagnetic structure was explained by a charge ordering defined among the different Ni sites, each one with different magnetic moments (1.4 and 0. low-spin configuration, because the amount of charge transfer for parallel spin almost equals that for antiparallel spin 13 . However, the spectral shape in RNiO 3 compounds is very sensitive to the transition from metallic to insulating states 15 and a complete description of the spin degree of freedom remains to be given. As in recent outcomes on Co 3+ oxides 16,17 , where unconventional spin states exist due to the competition between crystal field splitting and effective 3d exchange interaction, assignments made so far about Ni 3+ in RNiO 3 compounds have to be reexamined.We report here Ni L-edge absorption measurements, which probes directly the available Ni3d states, together with charge transfer multiplet calculations. We establish the importance of the cry...

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Probing the metal-insulator transition in Ni(III)-oxide perovskites

Cited by 72 publications

References 18 publications

Quantum confinement of Mott electrons in ultrathin LaNiO3/LaAlO3superlattices

Quantum confinement of Mott electrons in ultrathin LaNiO3/LaAlO3superlattices

Heterointerface engineered electronic and magnetic phases of NdNiO3 thin films

Spin-orbit-induced mixed-spin ground state inRNiO3perovskites probed by x-ray absorption spectroscopy: Insight into the metal-to-insulator transition

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