Effect of La/Al stoichiometry on transport and superconductivity at LaAlO3/SrTiO3 interfaces

Determine how variation of the La/Al cation ratio in LaAlO3 overlayers quantitatively affects carrier density, electron mobility, and the superconducting transition characteristics at LaAlO3/SrTiO3 interfaces, including the conditions under which superconductivity emerges or is suppressed.

Background

Conductivity at LaAlO3/SrTiO3 interfaces has been linked to mechanisms such as oxygen vacancies and polar discontinuity, with experimental work showing that interface conductivity depends on LaAlO3 stoichiometry, appearing only in Al-rich films below a critical La/Al ratio.

Despite this, a clear, quantitative understanding of how the La/Al stoichiometric ratio influences key transport parameters (carrier density and mobility) and the onset of superconductivity has been lacking, motivating dedicated investigation into stoichiometric control as an additional tuning knob beyond electrostatic gating.