Kondo Cloud in a Superconductor

Cătălin Paşcu Moca; Ireneusz Weymann; Miklós Antal Werner; Gergely Zaránd

doi:10.1103/PhysRevLett.127.186804

← Back to search

Kondo Cloud in a Superconductor

Cătălin Paşcu Moca, Ireneusz Weymann, Miklós Antal Werner, Gergely Zaránd

DOI 10.1103/PhysRevLett.127.186804 · Physical Review Letters

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

Magnetic impurities embedded in a metal are screened by the Kondo effect, signaled by the formation of an extended correlation cloud, the so-called Kondo or screening cloud. In a superconductor, the Kondo state turns into subgap Yu-Shiba-Rusinov states, and a quantum phase transition occurs between screened and unscreened phases once the superconducting energy gap Δ exceeds sufficiently the Kondo temperature, TK. Here we show that, although the Kondo state does not form in the unscreened phase, the Kondo cloud does exist in both quantum phases. However, while screening is complete in the screened phase, it is only partial in the unscreened phase. Compensation, a quantity introduced to characterize the integrity of the cloud, is universal, and shown to be related to the magnetic impurities’ g factor, monitored experimentally by bias spectroscopy.