Giant nonreciprocal charge transport in noncentrosymmetric LaAlO₃/SrTiO₃ interfaces

Electrons confined at an interfacial quantum well of a LaAlO₃/SrTiO₃ associated with broken inversion symmetry show various exotic condensed matter phases and rich spin-orbitronic functionalities. This two-dimensional polar conductor may exhibit directional propagation of itinerant electrons, i.e. the leftward and rightward currents differ from each other, when time-reversal symmetry is further broken. This potential rectification effect generally was displayed to be very weak due to the fact that kinetic energy is much higher than energies related to symmetry breakings producing weak perturbation. Here, we present giant gate-tunable nonreciprocal charge transport in the LaAlO₃/SrTiO₃ conductive oxide interface, where the electrons are confined at two-dimension with low Fermi energy. The coefficient γ indicating the magnitude of nonreciprocal response, was estimated to be as high as ~ 10² T^-1A^-1, which is about 3 order of magnitude higher than those reported for noncentrosymmetric conductors. The observed behavior of nonreciprocal response in LaAlO₃/SrTiO₃ is related to comparable energy scales among kinetic energy, magnetic field and spin-orbit interaction, which opens a promising route to improve nonreciprocal response and its functionalities in the emerging spin-orbitronics.