Films

Despite over 60 years of extensive research, the study of superconductivity, ferroelectricity and antiferrodistortive phase transition in SrTiO₃ remains puzzling yet intriguing. Through intrinsic defect management, we achieved for the first time electron density as low as 3 × 10¹⁷ cm^-3 in Sr_1-xNd_xTiO₃ films with the corresponding mobility exceeding 42000 cm²/vs at 1.8 K. By systematically varying the carrier density over three orders of magnitude, we present an important role of intra- vs. inter-band scattering on the superconducting transition temperature T_c across the Lifshitz transition. Significantly, we show a sizable effect of the antiferrodistortive phase transition on the normal state transport properties around 110 K. Finally, we discuss the role of dopant concentration, strain and dimensionality on the interplay between antiferrodistortive phase transition, incipient ferroelectricity, and normal and superconducting transport behavior in epitaxial Sr_1-xNd_xTiO₃ thin films grown by hybrid molecular beam epitaxy approach.