Abstract
In a Kondo lattice, the spin exchange coupling between a local spin and the conduction electrons acquires nonlocal contributions due to conduction electron scattering from surrounding local spins and the subsequent RKKY interaction. It leads to a hitherto unrecognized interference of Kondo screening and the RKKY interaction beyond the Doniach scenario. We develop a renormalization group theory for the RKKY-modified Kondo vertex. The Kondo temperature is suppressed in a universal way, controlled by the dimensionless RKKY coupling parameter . Complete spin screening ceases to exist beyond a critical RKKY strength even in the absence of magnetic ordering. At this breakdown point, remains nonzero and is not defined for larger RKKY couplings . The results are in quantitative agreement with STM spectroscopy experiments on tunable two-impurity Kondo systems. The possible implications for quantum critical scenarios in heavy-fermion systems are discussed.
- Received 8 December 2016
DOI:https://doi.org/10.1103/PhysRevLett.118.117204
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