Magnetic correlation between two local spins in a quantum spin Hall insulator

Zheng, Ru; He, Rong-Qiang; Lu, Zhong-Yi

doi:10.1103/physrevb.104.235134

Cited by 2 publications

(2 citation statements)

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“…(2). It has been demonstrated that the NORG is an effective method to study quantum impurity problems 79,80,82,[84][85][86] . Generally, the NORG method preserves the whole geometric information of a lattice, and its effectiveness is independent of any lattice structure or topology of a quantum impurity system.…”

Section: Model and Numerical Methodsmentioning

confidence: 99%

“…Therefore, it is interesting to investigate the Kondo effect in nanostructures such as topological GNRs. In addition, in a topological GNR with finite size, the helical edge states can come back by traversing the whole edge of the system, which may lead to distinct behaviors of the Kondo effect 78,79 , especially that in the system with a spin-1 2 impurity coupled to two helical liquids.…”

Section: Introductionmentioning

confidence: 99%

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Natural orbitals renormalization group approach to a Kondo singlet

Zheng

2020

Sci. China Phys. Mech. Astron.

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Using the natural orbitals renormalization group, we studied the problem of a localized spin-1 2 impurity coupled to two helical liquids via the Kondo interaction in a quantum spin Hall insulator, based on the Kane-Mele model defined in a finite zigzag graphene nanoribbon. We investigated the influence of the Kondo couplings with the helical liquids on both the static and dynamic properties of the ground state. The number and distinct spatial structures of the active natural orbitals (ANOs), which play essential roles in constructing the ground-state wave function, were first analyzed. Our numerical results indicate that two ANOs emerge, equal to the number of helical liquids. Specifically, at the coupling symmetry point, both ANOs are fully active with their spatial structures being respectively constituted by the different helical liquids. In comparison, when deviating from the symmetry point, only one ANO remains fully active, which is dominantly constructed by the helical liquid with the larger Kondo coupling. Local screening of the impurity, described by the impurity spin polarization and susceptibility, was further studied. It shows that at the coupling symmetry point, the impurity is maximally polarized and the spin susceptibility reaches the maximum. On the contrary, the impurity tends to be screened without polarization when the Kondo couplings deviate well from the symmetry point. The Kondo screening cloud, manifested by the spin correlation between the impurity and the conduction electrons, was finally explored. It is demonstrated that the Kondo cloud is mainly formed by the helical liquid with the larger Kondo coupling to the impurity. On the other hand, the spin-orbital coupling breaks the symmetry in spatial distribution of the spin correlation, leading to anisotropy in the Kondo cloud.

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