Modulation of quantum transport in complex oxide heterostructures with proton implantation

The interfacial electronic properties of complex oxides are governed by a delicate balance between charge transfer, lattice distortions, and electronic correlations, posing a key challenge for controlled tunability in materials research. Here, we demonstrate that proton implantation serves as a precise tool for modulating interfacial transport in SrTiO₃-based heterostructures. By introducing protons into the SrTiO₃ substrate beneath an amorphous (La,Sr)(Al,Ta)O₃ capping layer, we uncover competition between disorder and charge doping induced by implantation. At low implantation fluences below 1 × 10¹⁵ protons per cm² (1E15), the charge doping dominates, leading to an increase in carrier density and mobility, analogous to electrostatic gating effects. This enables the emergence of quantum transport oscillations at low temperature. Conversely, at higher fluences (above 1E15), disorder scattering prevails, suppressing carrier mobility and inducing an insulating state. The nonmonotonic evolution of transport with implantation fluence underscores the critical interplay between electronic correlations and disorder, offering a new paradigm for the controlled engineering of interfacial quantum states in SrTiO₃-based oxide heterostructures.