Phase coherence of conduction electrons below the Kondo temperature

Abstract

We have measured the phase decoherence rate, ${\tau }_{\varphi }^{-1}$ of conduction electrons in disordered Ag wires implanted with 2 and 10 parts per million Fe impurities, by means of the weak localization magnetoresistance. The Kondo temperature of Fe in Ag, $T_K\approx 4$ K, is in the ideal temperature range to study the progressive screening of the Fe spins as the temperature $T$ falls below $T_K$. The contribution to ${\tau }_{\varphi }^{-1}$ from the Fe impurities is clearly visible over the temperature range 40 mK -- 10 K. Below $T_K$, ${\tau }_{\varphi }^{-1}$ falls rapidly until $T/T_K\approx 0.1$, in agreement with recent theoretical calculations. At lower $T$, ${\tau }_{\varphi }^{-1}$ deviates from theory with a flatter $T$-dependence. We speculate that this latter behavior is due to incomplete screening of the s=2 Fe impurities by the conduction electrons.

4 pages, 3 figures, 1 table

References in corpus (4)

• Theory of inelastic scattering from magnetic impurities
• Universal dephasing rate due to diluted Kondo impurities
• Scaling of the low temperature dephasing rate in Kondo systems
• Experimental Test of the Numerical Renormalization Group Theory for Inelastic Scattering from Magnetic Impurities

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