Enhancement of Kondo effect through Rashba spin- orbit interactions: application to graphene

The role of Rashba spin-orbit (RSO) interactions on the Kondo regime has been a topic of debate

since resistivity measurements on Pt doped Cu:Mn compounds were interpreted as evidence for

suppression of the Kondo effect by SO scattering. Since then, extensive theoretical and

experimental works have yielded conflicting results. In order to provide a clearer picture, we

have undertaken the study of an Anderson magnetic impurity model in a two-dimensional

metallic host with RSO interactions. We show that at the particlehole symmetry point, the

corresponding Hamiltonian for a single-channel Kondo regime is recovered. However, away

from particle-hole symmetry, a new term appears that shows the existence of the Dzyaloshiinski-

Moriya (DM) interaction between bath and impurity spins. Renormalization group equations

reveal that the impurity couples to the bath with ferroand antiferromagnetic couplings, with the

DM interactions introducing an exponential increase in the value of the Kondo temperature [1].

As a particular system of interest, we focus on non-suspended graphene with magnetic

impurities on top. After reviewing the effect of RSO interactions on graphene [2]. I will discuss

the resulting Kondo regime when magnetic impurities are included.

[1] M. Zarea, S. E. Ulloa, and N. Sandler, arXiv:cond-mat 1105.3522 (2011).

[2] M. Zarea and N. Sandler, Phys. Rev. B 79, 155442 (2009).

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