Screening mechanisms in magnetic nanostructures

Abstract

A theoretical concept is presented for the screening of several magnetic moments locally exchange coupled to conduction electrons in a metallic nanostructure. We consider a quantum confined multi-impurity Kondo model which exhibits the competition between finite-size effects, RKKY interactions, and Kondo physics. In the limit of weak coupling, Kondo correlations are cut by the finite system size; perturbation theory can then be used to derive the low-energy effective model, which is of generalized central-spin form. The theory successfully predicts the degeneracy, total spin, and spin correlations of the ground state, and allows the number of screening channels to be identified. This is demonstrated for a two-impurity model on a finite one-dimensional ring. Density-matrix renormalization-group calculations confirm the physical picture at weak coupling. The non-trivial crossovers to RKKY and strong-coupling regimes are also studied. The numerical renormalization group, tailored to treat finite systems, is used to examine the crossover to the thermodynamic limit.

14 pages, 9 figures, v2 with minor corrections

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Cited by in corpus (12)

• Interleaved numerical renormalization group as an efficient multiband impurity solver
• Competition between Kondo effect and RKKY physics in graphene magnetism
• Effective low-energy description of the two impurity Anderson model: RKKY interaction and quantum criticality
• Validity of the local self-energy approximation: Application to coupled quantum impurities
• Quantum impurities in channel mixing baths
• Natural orbitals renormalization group approach to a Kondo singlet
• Ground-state properties of the symmetric single-impurity Anderson model on a ring from Density-Matrix Renormalization Group, Hartree-Fock, and Gutzwiller theory
• Spin-1 two-impurity Kondo problem on a lattice
• Nonequilibrium Kondo-vs-RKKY Scenarios in Nanoclusters
• Non-Hamiltonian dynamics of indirectly coupled classical impurity spins
• Realistic indirect spin-interactions between magnetic impurities on a metallic Pb(110) surface
• Kondo Screening and Indirect Magnetic Exchange through a Conventional Superconductor Studied by the Density-Matrix Renormalization Group