Experimental Test of the Numerical Renormalization Group Theory for Inelastic Scattering from Magnetic Impurities

We present measurements of the phase coherence time \tauphi in quasi one-dimensional Au/Fe Kondo wires and compare the temperature dependence of \tauphi with a recent theory of inelastic scattering from magnetic impurities (Phys. Rev. Lett. 93, 107204 (2004)). A very good agreement is obtained for temperatures down to 0.2 $T_K$. Below the Kondo temperature $T_K$, the inverse of the phase coherence time varies linearly with temperature over almost one decade in temperature.Comment: 5 pages, 3 figure

Thermoelectric Power of Gd₄(Co-A)₃ Compounds (A = Cu, Pt)

We report on a comparative study of thermoelectric power measurements (S(T)) in ferrimagnetic Gd4(Co1-xAx)3 compounds with A = Cu, Pt, in the temperature range 8 K – 300 K. Whereas in Gd4Co3S(T) is always negative, for x &gt; 0 the substitution of Co for Cu/Pt gives rise to the appearance of a low temperature positive maximum in S(T) at around 30 K. Based on our previous study of Gd4(Co1-xCux)3 compounds, we argue that this maximum in S(T) originates from electron-magnon scattering and is sensitive to electron band structure changes resulting from the substitution of Co for Cu/Pt and the accompanying reduction in the ratio between the electron-magnon and the electron-phonon scattering strengths. The decreasing role of Co 3d electrons with the progressive substitution of Co for Cu/Pt, evidenced by a strong reduction in the spin disorder resistivity and the Co magnetic moment, is seen to be crucial for the existence of such low temperature maximum in S(T) for x &gt; 0. It is seen that the substitution of Co for Pt leads to higher values of the amplitude and temperature of the positive maximum in S(T) than the substitution of Co for Cu.</jats:p