Enhancement of the Kondo temperature of magnetic impurities in metallic point contacts due to the fluctuations of the local density of states

The effect of local density of states (LDOS) fluctuations on the dynamics of a Kondo impurities in a small metallic point contact (PC) is studied. To estimate the spatial and energy-dependent LDOS fluctuations we investigate a model PC by means of a transfer matrix formalism. For small PC’s in the nanometer scale we find that near to the orifice strong LDOS fluctuations develop. These fluctuations may shift the Kondo temperature by several orders of magnitude, and result in a strong broadening of the PC Kondo peak in agreement with the results of recent measurements. © 1996 The American Physical Society.