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arXiv · 1809.07422

From Kondo effect to weak-link regime in quantum spin-1/2 spin chains

Domenico Giuliano·Davide Rossini·Andrea Trombettoni
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Abstract

We analyze the crossover from Kondo to weak-link regime by means of a model of tunable bond impurities in the middle of a spin-1/2 XXZ Heisenberg chain. We study the Kondo screening cloud and estimate the Kondo length by combining perturbative renormalization group approach with the exact numerical calculation of the integrated real-space spin-spin correlation functions. We show that, when the spin impurity is symmetrically coupled to the two parts of the chain with realistic values of the Kondo coupling strengths and spin-parity symmetry is preserved, the Kondo length takes values within the reach of nowadays experimental technology in ultracold-atom setups. In the case of non-symmetric Kondo couplings and/or spin parity broken by a nonzero magnetic field applied to the impurity, we discuss how Kondo screening redistributes among the chain as a function of the asymmetry in the couplings and map out the shrinking of the Kondo length when the magnetic field induces a crossover from Kondo impurity to weak-link physics.

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Domenico Giuliano, Davide Rossini, Andrea Trombettoni. 2018-12-29. From Kondo effect to weak-link regime in quantum spin-1/2 spin chains. https://doi.org/10.1103/physrevb.98.235164

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