Quasi 2D correlated metals: Unusual transport properties in strained heteroepitaxial ultrathin films*

We explore the electrical transport and magnetoconductance in quasi 2D strongly correlated heteroepitaxial films of LaNiO$_3$ to investigate the effect of quantum confinement and strain on electron-electron and electron-lattice interactions over the whole temperature range (2-300K) including the effect of metal-insulator transition. The quantum corrections to the conductivity indicate that the combination of the weak localization and the electron-electron interaction in the quasi 2D limit gives rise to unusual T-dependent resistivity. Ultrathin films spanning tensile strain up to $\sim$4$\%$ are used to obtain the enhanced driving effects between the two corrections for the observed localization at low temperatures. Intrinsic transport properties of strained LaNiO$_3$ films with the characteristic multi-band structure will be discussed.