CPM Seminar

The Kondo screening cloud:
what it is and how to measure it in a gated semi-conductor device

Ian Affleck

Department of Physics
University of British Columbia

The screening of a magnetic impurity by conduction electrons is widely believed to be associated with the formation of a spin singlet with a conduction electron in a very extended wave-function with size of order h/2π v_F/<(k_BT_K) where T_K is the Kondo temperature, typically .1 to 1 micron. However, no experiment has every measured this enormous length scale and its very existence has sometimes been questioned. I will review the theory of this Kondo screening cloud and suggest an experiment involving a gated semi-conductor quantum dot and a quantum wire which might finally observe it.