Suppression of the Kondo effect in a quantum dot by microwave radiation

We have studied the influence of microwave radiation on the transport properties of a semiconductor quantum dot in the Kondo regime. In the entire frequency range tested (10-50 GHz), the Kondo resonance vanishes by increasing the microwave power. This suppression of the Kondo resonance shows an unexpected scaling behavior. No evidence for photon-sideband formation is found. The comparison with temperature-dependence measurements indicates that radiation-induced spin dephasing plays an important role in the suppression of the Kondo effect.