Phase coherence of conduction electrons below the Kondo temperature

The scattering of conduction electrons by magnetic impurities is known as the Kondo effect. This effect has been the subject of theoretical and experimental investigations for several decades. Until very recently [1, 2], however, there was no theoretical expression for the temperature dependence of the inelastic scattering rate valid for temperatures $T $not too far below the Kondo temperature, $T_{K}$. We present experimental measurements of the phase decoherence rate, $\tau _{\phi }^{-1}$, of conduction electrons in disordered dilute AgFe Kondo wires [3]. We compare the temperature dependence of the magnetic scattering rate, $\gamma _{m}$, with a recent theory of dephasing by Kondo impurities [2]. A good agreement with theory is obtained for $T$/$T_{K }>$ 0.1. At lower $T$, $\gamma _{m}$ deviates from theory with a flatter $T$-dependence. \newline \newline [1] G. Zarand, L. Borda, J. von Delft, and N. Andrei, Phys.Rev. Lett. 93, 107204 (2004). \newline [2] T. Micklitz, A. Altland, T. A. Costi, A. Rosch, Phys.Rev. Lett. 96, 226601 (2006). \newline [3] G.M. Alzoubi and N.O. Birge, Phys.Rev. Lett. in press (2006).