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

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.

27 pages, 12 .eps figures, version published in PRB

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Cited by in corpus (9)

• Lindblad equation approach to the optimal working point in nonequilibrium stationary states of an interacting electronic one-dimensional system: Application to the spinless Hubbard chain in the clean and in the weakly disordered limit
• Multi-particle scattering and breakdown of the Wiedemann-Franz law at a junction of N interacting quantum wires
• Tunable Kondo screening length at a Y-junction of three inhomogenous spin chains
• Kondo effect in the isotropic Heisenberg spin chain
• Tunable spin/charge Kondo effect at a double superconducting island connected to two spinless quantum wires
• Edge modes and boundary impurities in the anisotropic Heisenberg spin chain
• Two Channel Kondo behavior in the quantum XX chain with a boundary defect
• Spin and thermal current scaling at a $Y$-junction of XX spin chains
• Geometric phase and topological phase diagram of the one-dimensional $XXZ$ Heisenberg spin chain in a longitudinal field