Phase Diagram of Micron-Size Bridges of SrTiO₃/LaAlO₃ Interface: Link Between Multiple Band Structure and Superconductivity

The rich phase diagram of the two dimensional electron gas (2DEG) at the \STO/\LAO interface is probed using Hall and longitudinal resistivity. Thanks to a special bridge design we are able to tune through the superconducting transition temperature T$_c$ and to mute superconductivity by either adding or removing carriers in a gate bias range of a few volts. Hall signal measurements pinpoint the onset of population of a second mobile band right at the carrier concentration where maximum superconducting T$_c$ and critical field H$_c$ occur. These results emphasize the advantages of our design, which can be applied to many other two dimensional systems assembled on top of a dielectric substrate with high permittivity.