A metal-insulator transition tunable by lattice deformation in LaTiO$_{3}$ thin films

Strong electron-electron and electron-lattice correlations play critical roles in electronic transitions of complex oxides. Since LaTiO$_{3}$ is a narrow bandgap Mott insulator on the verge of a metal-insulator transition, substrate-induced lattice distortions offer a route to tuning its electronic properties. We have observed metallic to insulating behavior in LaTiO$_{3}$ films depending on choice of (001) substrates: SrTiO$_{3}$, LSAT, and LaAlO$_{3}$. Tetragonal distortions induced by epitaxial in-plane compression from the SrTiO$_{3}$ substrates result in metallicity in LaTiO$_{3}$ films, while films on LSAT substrates exhibit a range of electronic properties depending on the degree of lattice relaxation. Whereas thinner LaTiO$_{3}$ films on LSAT exhibit ``semimetallic'' behavior, in thicker films, the out-of-plane lattice parameters surprisingly converge to values greater than the bulk lattice constant, and the films become more insulating. We will discuss the profound consequences thin-film lattice deformation has on electrical transport. We speculate that stabilization of lattice distortions via epitaxy may open a new avenue for materials engineering of oxides through careful control of structural perturbations.