Content
Analyzing the anisotropic Kondo-effect with NRG
Wael Chibani
15.12.2010 at 16:00
Abstract:
Using the numerical renormalization group (NRG), we study the STM tunneling current through a Co atom embedded on an anisotropic lattice and experiencing a magnetic field in both directions, parallel and perpendicular to the anisotropy, as was measured by Otte et al. [1]. We introduce the Kondo-Anderson hybrid model (KAHM) Hamiltonian, by which we describe the system, where we take the spin of the Co atom as being S=3/2, and present the mapping of the self energy representation [2] onto our model. After discussing the easy-axis and easy-plan anisotropy, we demonstrate, that our problem is best described by an easy-axis anisotropy. Moreover, the experimental spectra show a dependence of the splitting of the Kondo resonance at finite magnetic fields on the direction of the magnetic field with respect to the anisotropy, which we will also discuss.
Finally, when comparing our NRG calculated current with the experimentally measured one, we found, that, the Kondo temperature as given in the experiment is too small and thus, we choose an effective temperature to describe the system.
[1] Otte A. F., Ternes. M., von Bergmann K., Loth S., Brune H. Lutz C. P., Hirjibehedin C. F. and Heinrich A. J., Nature Physics, Vol 4, November 2008.
[2] Bulla R., Hewson A. C. and Pruschke T., J.Phys. : Condens. Matter 10, 8365- 8380 (1998).
Room A 450, Theresienstr. 37 , LMU