Spin-1 two-impurity Kondo problem on a lattice

Article

关键词: D EXCHANGE MODEL;    RENORMALIZATION-GROUP;    ANDERSON MODEL;    MAGNETIC-ANISOTROPY;    EXCITATION-SPECTRA;    GROUND-STATE;    TRANSITION;    POINT;   

DOI  :  10.1103/PhysRevB.97.045103

来源: SCIE

【 摘 要 】

We present an extensive study of the two-impurity Kondo problem for spin-1 adatoms on a square lattice using an exact canonical transformation to map the problem onto an effective one-dimensional system that can be numerically solved using the density matrix renormalization group method. We provide a simple intuitive picture and identify the different regimes, depending on the distance between the two impurities, Kondo coupling J(K), longitudinal anisotropy D, and transverse anisotropy E. In the isotropic case, two impurities on opposite (the same) sublattices have a singlet (triplet) ground state. However, the energy difference between the triplet ground state and the singlet excited state is very small and we expect an effectively fourfold-degenerate ground state, i.e., two decoupled impurities. For large enough J(K) the impurities are practically uncorrelated forming two independent underscreened states with the conduction electrons, a clear nonperturbative effect. When the impurities are entangled in an RKKY-like state, Kondo correlations persist and the two effects coexist: the impurities are underscreened, and the dangling spin-1/2 degrees of freedom are responsible for the interimpurity entanglement. We analyze the effects of magnetic anisotropy in the development of quasiclassical correlations.

【 授权许可】

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