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

Abstract

The Kondo effect has been a topic of intense study because of its significant contribution to the development of theories and understanding of strongly correlated electron systems. In this work, we show that the Kondo effect is at work in La1−xPrxNiO3−δ (0 ≤ x ≤ 0.6) thin films. At low temperatures, the local magnetic moments of the 3d eg electrons in Ni2+, which form because of oxygen vacancies, interact strongly with itinerant electrons, giving rise to an upturn in resistivity with x ≥ 0.2. Observation of negative magnetoresistance, described by the Khosla and Fisher model, further supports the Kondo picture. This case represents a rare example of the Kondo effect, where Ni2+ acts as an impurity in the background of Ni3+. We suggest that when Ni2+ does not participate in the regular lattice, it provides the local magnetic moments needed to scatter the conduction electrons in the Kondo effect. These results offer insights into emergent transport behaviors in metallic nickelates with mixed Ni3+ and Ni2+ ions, as well as structural disorder.

Elucidating the Role of B-Site Cations toward CO2 Reduction in Perovskite-Based Solid Oxide Electrolysis Cells

“…50,51 The appearance of the new feature at 72 eV could be linked both to a satellite peak of Ni 2+ oxidation state 52 and/or to the decreased intensity of the Ni 3+ feature, which some references locate at around 71 eV. [53][54][55] Independent of the slightly different interpretations of the Ni 3p data, the XPS results were consistent with the findings from XRD, suggesting that LaNiO 3 was the only redox unstable perovskite under the considered electrochemical conditions.…”

Synergistic Role of Eg Filling and Anion–Cation Hybridization in Enhancing the Oxygen Evolution Reaction Activity in Nickelates

“…X-ray photoelectron spectroscopy (XPS) (Supporting Information Figure S7) also confirms our DFT calculations. By fitting the Ni 3p peaks with three Gaussian functions representing components of Ni 3+ , Ni 2+ , and satellite peaks as widely employed in the literature, 44,45 the intensity of Ni 3+ enhances monotonously with increasing n value, showing the average Ni valence indeed increases as expected.…”

The Origin of the Low-Temperature Minimum of Electrical Resistivity in Strontium Ferromolybdate Ceramics

“…The ratio T 1 /T 0 defines a value of the product χw of the reciprocal localization length of the wave function χ and barrier width w. Since the value of the tunnel barrier height V 0 depends on the nature and configuration of chemical bonds in the intergrain area, the differences in V 0 for different SFMO materials should be small. For given values of V 0 , the value of χ can be calculated by means of Equation (12). The barrier width w then defines T 1 /T 0 via Equation (11).…”

“…Generally, several mechanisms have been discussed to interpret the low-temperature resistivity upturn that was visible in experiments: (i) inelastic scattering of electrons by impurity ions in impure metals [9], (ii) Kondo-like effects associated with dilute magnetic impurities in a nonmagnetic host [10][11][12][13][14], (iii) quantum interference effects arising from electron-electron interactions and weak localization [15][16][17][18][19][20][21][22], (iv) electron-electron interaction driven by Coulomb forces in a strongly correlated system [23], (v) spin-polarized tunneling via grain boundaries in ceramic manganites [24], (vi) the competition of two mechanisms-one contribution decreasing with temperature combined with another contribution increasing with temperature [10,25], and (vii) two spin channels in SFMO connected in parallel, where the spin-down channel is metallic (with a non-zero density of states at the Fermi level), and the spin-up channel (with a gap in the band structure) behaves like a semiconductor [26].…”