Competition between Kondo effect and RKKY physics in graphene magnetism

Article

关键词: LOCAL ATOMIC ENVIRONMENT;    RENORMALIZATION-GROUP;    SUSCEPTIBILITY;    IMPURITY;    ANDERSON;    STATE;   

DOI  :  10.1103/PhysRevB.95.104402

来源: SCIE

【 摘 要 】

The cooperative behavior of quantum impurities on two-dimensional (2D) materials, such as graphene and bilayer graphene, is characterized by a nontrivial competition between screening (Kondo effect) and RudermanKittel- Kasuya-Yosida (RKKY) magnetism. In addition, due to the small density of states at the Fermi level, impurities may not couple to the conduction electrons at all, behaving as free moments. Employing a recently developed exact numerical method to study multi-impurity lattice systems, we obtain nonperturbative results that dramatically depart from expectations based on the conventional RKKY theory. At half filling and for weak coupling, impurities remain in the local moment regime when they are on opposite sublattices, up to a critical value of the interactions when they start coupling antiferromagnetically with correlations that decay very slowly with interimpurity distance. At finite doping, away from half filling, ferromagnetism is completely absent and the physics is dominated by a competition between antiferromagnetism and Kondo effect. In bilayer graphene, impurities on opposite layers behave as free moments, unless the interaction is of the order of the hopping or larger.

【 授权许可】

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