Unusual Scaling of Kondo Spin Relaxation

TL;DR

This study investigates the relationship between Kondo spin and momentum relaxation rates in copper channels with iron impurities, revealing unexpected behavior that supports the existence of Kondo screening clouds.

Contribution

It uncovers a surprising independence of spin relaxation rate from impurity concentration, challenging existing models and supporting the physical reality of Kondo clouds.

Findings

Linear relation between ${ au_{sK}}^{-1}$ and ${ au_{eK}}^{-1}$ under temperature variation.

${ au_{sK}}^{-1}$ remains nearly constant despite impurity concentration changes.

Supports the physical existence of Kondo screening clouds.

Abstract

The relation between the Kondo spin relaxation rate $ {\tau_{sK}}^{-1} $ and the Kondo momentum relaxation rate $ {\tau_{eK}}^{-1} $ is explored by using nonlocal spin valves with submicron copper channels that contain dilute iron impurities. A linear relation between $ {\tau_{sK}}^{-1} $ and $ {\tau_{eK}}^{-1} $ is established under varying temperatures. However, under varying impurity concentrations, ${\tau_{sK}}^{-1}$ remains nearly constant despite variation of $ {\tau_{eK}}^{-1} $ by a factor of 10. This surprising relation can be understood by considering spin relaxation through overlapping Kondo screening clouds and supports the physical existence of the elusive Kondo clouds.