Long-Range Non-Coulombic Electron–Electron Interactions between LaAlO₃/SrTiO₃ Nanowires

The LaAlO₃/SrTiO₃ system exhibits unusual magnetic and superconducting behavior arising from electron–electron interactions whose physical origin is not well understood. Quantum transport techniques, especially those involving mesoscopic geometries, can offer insight into these interactions. Here evidence for long-range electron–electron interactions in LaAlO₃/SrTiO₃ nanowires, measured through the phenomenon of frictional drag, is reported, in which current passing through one nanowire induces a voltage across a nearby electrically isolated nanowire. Frictional drag mediated by the Coulomb interaction is predicted to decay exponentially with interwire separation, but with the LaAlO₃/SrTiO₃ nanowire system it is found to be nearly independent of separation. Frictional drag experiments performed with three parallel wires demonstrate long-range frictional coupling even in the presence of an electrically grounded central wire. Collectively, these results provide evidence for a new long-range non-Coulombic electron–electron interaction unlike anything previously reported for semiconducting systems.