Joint effect of composition and strain on the anomalous transport properties of LaNiO3 films

In the present work, epitaxial LaNi1−xO3 films were grown on SrTiO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and LaAlO3 substrates by pulsed laser deposition from targets with different Ni stoichiometry. Effect of Ni content on the transport properties of LaNiO3 films was investigated under different strain states. It is found that under tensile strain the carriers in the LaNi0.98O3 films behave according to the Fermi-liquid theory, while under compressive strain an anomalous T1.5 dependence of the resistivity which does not agree with the Fermi-liquid theory is observed in the films. On the other hand, only T1.5 dependence is observed in the LaNi1.20O3 films irrespective of strain states. The results show that strain has a profound influence on the transport properties of LNO films with Ni deficiency and the effect of strain is eliminated in the LNO films with excess Ni. Combined with the XRD results, it is proposed that the change in transport behavior is closely related to the stoichiometry of the LNO films. The mechanism behind is investigated based on the intrinsic and extrinsic factors of the films under different strains.