Quantized Conductance in a One-Dimensional Ballistic Oxide Nanodevice

The electric-field effect control of two-dimensional electron gases (2DEG) has allowed nanoscale electron quantum transport to be explored in semiconductors. Structures based on transition metal oxides have electronic states that favour the emergence of novel quantum orders that are absent in conventional semiconductors and the 2DEG formed at a LaAlO3/SrTiO3 interface —a structure in which superconductivity and spin–orbit coupling can coexist— is a promising platform to develop devices for spintronics and topological electronics. However, field-effect control of the properties of this interface at the nanoscale remains challenging. In this presentation we show that a quantum point contact can be formed in a LaAlO3/SrTiO3 interface through electrostatic confinement of the 2DEG using a split gate. Our device exhibits a quantized conductance due to ballistic transport in a controllable number of one-dimensional conducting channels. Under a magnetic field, the direct observation of the Zeeman splitting between spin-polarized bands allows the determination of the Landé g-factor, whose value differs strongly from that of free electrons. Through source–drain voltage measurements, were also performed a spectroscopic investigation of the 3d energy levels inside the quantum point contact.