Kondo-Resonance Mediated Metal-Insulator Transition in GaAs Embedded with Erbium Arsenide Quantum Dots

We report anomalous critical transport behavior in a GaAs structure containing a dense array of ErAs quantum dots. The structure displays a voltage (electric field)-controlled insulator-to-metal transition and strong hysteresis in the Kondo-like current-vs-temperature characteristic, with critical temperatures as high as 50 K. We attribute this behavior to a strong distributed Kondo resonance between the quantum dots after the Coulomb blockade of the array is lifted. This is consistent with a high sensitivity of the phase transition to a small external magnetic field that we have observed in the Voigt configuration, and a phenomenological model based on the RKKY interaction within a quantum dot and the cooperative Kondo-resonance amongst quantum dots.