Stoichiometry-Control of Electronic Transport at Complex Oxide Interface

Employing the hybrid molecular beam epitaxy approach to grow NdTiO$_{\mathrm{3}}$/SrTiO$_{\mathrm{3}}$ heterostructures - a polar/nonpolar system sharing many similarities with LaAlO$_{\mathrm{3}}$/SrTiO$_{\mathrm{3}}$ with an added functionality of NdTiO$_{\mathrm{3}}$ being an antiferromagnetic Mott insulator- we will present a detailed film growth and transport study as a function of cation stoichiometry in NdTiO$_{\mathrm{3}}$. Irrespective of the cation stoichiometry (measured by high resolution x-ray diffraction and x-ray photoelectron spectroscopy), films grew in an atomic layer-by-layer fashion as evidenced by the reflection high-energy electron diffraction intensity oscillations, and films showed a temperature dependent metal-to-insulator (M-I) type behavior. Remarkably, T$_{\mathrm{MI}}$ was found to increase irrespective of whether films were Nd- or Ti-rich. Furthermore, hall measurement of a 3.5 nm NdTiO$_{\mathrm{3}}$ film grown on 3 nm SrTiO$_{\mathrm{3}}$ layer on LSAT substrate revealed n type carrier density, 3 x 10$^{\mathrm{14}}$ cm$^{\mathrm{-2}}$ for stoichiometric samples, which would be consistent with the interface conduction due to an interfacial polar discontinuity effect. Using detailed temperature dependent magneto-transport measurements, we will present a comprehensive study of correlation between film stoichiometry, interface conduction, and transport mechanisms.