Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Correlated Electrons: Quantum Impurities, Kondo Physics

TT 30.3: Talk

Tuesday, March 12, 2013, 10:00–10:15, H21

Kondo effect and magnetic frustration in a system of magnetic trimer on a metal surface — •Hoa Nghiem — Forschungszentrum Jülich, PGI-2/IAS-3, Jülich, Germany

We use quantum Monte Carlo simulation to clarify the competition between Kondo screening and magnetic frustration in a system of three magnetic adatoms on a metal surface [1]. We observe the feature of spectral density depending on the geometric configuration of three magnetic adatoms on the surface [2, 3]. In the isosceles configuration, the spectral density exhibits a significant peak near the Fermi level, which we attribute to the Yosida-Kondo resonance. In the equilateral configuration, no peak is observed near the Fermi level. This observation suggests the two separate regimes; the Yosida-Kondo dominant regime with the singlet ground state, and the magnetic frustration dominant regime with the degenerate ground state, - changing from one regime to another is realized as we gradually switch the geometric configuration from the isosceles triangle to equilateral one. By calculating the spectral density and the magnetic susceptibility in a wide range of temperatures, we prove the existence of the two separate regimes and suggest the critical crossover between them.
[1] N. T. M. Hoa, W. A. Diño, and H. Kasai: J. Phys. Soc. Jpn. 81 (2012) 023706
T . Jamneala, V. Madhavan, and M. F. Crommie: Phys. Rev. Lett 87 (2001) 256804
N. T. M. Hoa, W. A. Diño, and H. Kasai: J. Phys. Soc. Jpn. 79 (2010) 113706