97 39286LaNiO 3 (LNO) thin films were grown using pulsed laser deposition. The c-axis, i.e., out-of-plane lattice parameter of the films was controlled reproducibly by using different substrate materials and by variation of oxygen partial pressure and growth temperature. The out-of-plane (c-axis) strain of LNO deposited on LaAlO 3 with increasing oxygen pressure changed from positive to negative. All the films show an excellent metallic conductivity with positive resistivity temperature coefficient. Lowest resistivity was about 300 mV cm. At high and low temperatures, the resistivity is explained by electron-phonon scattering and electron-electron interaction, respectively. In addition, the resistivity shows a clear dependence on the c-axis strain of LNO films. With increasing strain, the resistivity increases. However, this effect is much more pronounced for negative c-axis strain.Strain-dependent resistivity of LNO films on LAO at the indicated measurement temperatures. The inset is a typical AFM image of the LNO film surface.1 Introduction The conduction band of perovskite nickelates (RNiO 3 , where R ¼ rare earth) is formed by the overlap of the Ni 3d orbitals and the O 2p orbitals. Most perovskite nickelates exhibit a temperature-driven metal-toinsulator transition [1,2], which is related to the strongly distorted perovskite structure and the size of the rare-earth ion R [3, 4]. However, LaNiO 3 (LNO) is the only member that remains metallic down to the lowest temperatures [5]. For this reason, LNO is an excellent candidate for use as an electrode in oxide electronics, in particular at low temperature. The primitive cell of bulk LNO is rhombohedral with angle a ¼ 60.498. It is reasonably well approximated by a pseudocubic cell with a ¼ 0.3838 nm. Several efforts have been undertaken to prepare LNO thin films by sputtering [6], pulsed laser deposition (PLD) [7], molecular beam