Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 7: Electronic Structure of Surfaces: Magnetism and Spin Phenomena

O 7.4: Talk

Monday, March 20, 2017, 11:15–11:30, WIL C107

Inelastic Electron Tunneling: Selection Rules and Orbital Exchange — •Jindrich Kolorenc — Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic

We investigate tunneling of electrons from an STM tip to a substrate through a magnetic adatom by means of the Anderson impurity model. We employ an approximation analogous to the cotunneling theory [1] and concentrate on f-electron adatoms with large spin-orbital coupling. We compare the obtained inelastic electron tunneling spectra (IETS) with predictions of the spin model that has been very successful in the case of transition-metal adatoms [2]. When the spin model is applied to f electrons, the adatom spin S is replaced with its angular momentum J [3,4]. The spectra calculated in the two models differ, and we trace this difference to the exchange interaction between the adatom and the tunneling electrons. The bilinear (Heisenberg) exchange J·s, assumed in the spin model [3,4], implies a selection rule Δ m_J=0,±1 for single-electron scatterings, whereas the Anderson model indicates a larger number of allowed scattering channels. The less restrictive selection rule originates in the orbital exchange that is active for the orbital contribution to the magnetic moment of the adatom. This more general exchange influences also the lifetime of the magnetic states since they are destabilized, among other mechanisms, by the exchange with substrate electrons [4]. [1] F. Delgado and J. Fernández-Rossier, Phys. Rev. B 84, 045439 (2011), [2] M. Ternes, New. J. Phys. 17, 063016 (2015), [3] T. Schuh et al., Phys. Rev. B 84, 104401 (2011), [4] T. Miyamachi et al., Nature 503, 242 (2013).