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Local Defect in Metallic Quantum Critical Systems

A. J. Millis·D. K. Morr·J. Schmalian
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Abstract

We present a theory of a single point, line or plane defect coupling to the square of the order parameter in a metallic system near a quantum critical point at or above its upper critical dimension. At criticality, a spin droplet is nucleated around the defect with droplet core size determined by the strength of the defect potential. Outside the core a universal slowly decaying tail of the droplet is found, leading to many dissipative channels coupling to the droplet and to a complete suppression of quantum tunneling. We propose an NMR experiment to measure the impurity-induced changes in the local spin susceptibility.

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A. J. Millis, D. K. Morr, J. Schmalian. 2001-04-13. Local Defect in Metallic Quantum Critical Systems. https://doi.org/10.1103/physrevlett.87.167202

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