Nanowires*

Frictional drag, where current in one nanowire induces a voltage across a nearby nanowire, is a powerful tool to study electron interactions. Here we investigate long-range electron interactions in coupled nanowires at the LaAlO₃/SrTiO₃ interface via frictional drag. In the normal state (B > 0.3T) regime, the antisymmetric drag resistance of double-wire devices is independent of their separation, ruling out the Coulomb interaction as the dominant coupling mechanism. In triple-wire devices this separation independence is corroborated. In the superconducting (B < 0.3T, T < 300mK) regime, a symmetric component is identified in the drag resistance and its separation independence also shows the coupling is predominantly non-Coulombic. These results provide strong evidence for a new long-range non-Coulombic electron interaction that must be accounted for in description of electron transport at oxide interfaces.