Tunable resistivity exponents in the metallic phase of epitaxial nickelates

Qikai Guo,Beatriz Noheda,Saeedeh Farokhipoor,César Magén,Francisco Rivadulla

doi:10.1038/s41467-020-16740-5

Qikai Guo, Beatriz Noheda + Show 3 more

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https://doi.org/10.1038/s41467-020-16740-5

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Abstract

We report a detailed analysis of the electrical resistivity exponent of thin films of NdNiO3 as a function of epitaxial strain. Thin films under low strain conditions show a linear dependence of the resistivity versus temperature, consistent with a classical Fermi gas ruled by electron-phonon interactions. In addition, the apparent temperature exponent, n, can be tuned with the epitaxial strain between n = 1 and n = 3. We discuss the critical role played by quenched random disorder in the value of n. Our work shows that the assignment of Fermi/Non-Fermi liquid behaviour based on experimentally obtained resistivity exponents requires an in-depth analysis of the degree of disorder in the material.

Highlights

We report a detailed analysis of the electrical resistivity exponent of thin films of NdNiO3 as a function of epitaxial strain
Liu et al.[42] obtained n = 5/3 and n = 4/3 for NdNiO3 (NNO) films under compressive strain, while Mikheev et al reported a crossover between Fermi liquid (FL) (n = 2) and Non-Fermi liquid’ (NFL) (n = 5/3) in NNO films with varying epitaxial strain[43]
Crystalline NNO films have been grown by pulsed laser deposition (PLD) on -oriented LaAlO3 (LAO), NdGaO3 (NGO), SrTiO3 (STO) substrates and -oriented DyScO3 (DSO) substrates, using a single-phase ceramic target

Summary

Introduction

We report a detailed analysis of the electrical resistivity exponent of thin films of NdNiO3 as a function of epitaxial strain. Among strongly correlated electron materials, nickelates (RENiO3, with RE denoting a trivalent rare-earth element) present a very interesting case They have attracted attention due to their MIT18 and the possibility to tune it using different RE elements or by epitaxial strain[19,20,21,22,23,24]. It has been reported that eliminating the MIT in nickelates by orbital engineering would give rise to a superconducting state[39], with a very recent experimental achievement in this direction[40] It becomes, important to have an accurate picture of the relevant electron interactions in the intermediate- and low-temperature regimes, just before the MIT takes place. The need for an empirical parallel resistor model to introduce the effect of the saturation resistivity rises questions about the interpretation of the apparent (experimentally obtained) exponents, as discussed by Hussey et al.[47]

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