- 08.10.2019 -
S3 SEMINAR Dr. Jindrich Kolorenc
Date and Time: Tuesday October 08, 2019 - 11.00
Venue: S3 Seminar Room, Third Floor, Physics Building, FIM Department
Speaker: Dr. Jindrich Kolorenc, PhD
Department of Condensed Matter Theory Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
Title: Inelastic Electron Tunneling through an Adatom: Selection Rules and Orbital Exchange
Abstract:
I investigate tunneling of electrons from an STM tip to a substrate
through a magnetic adatom by means of the Anderson impurity model. I
employ an approximation analogous to the cotunneling theory [1] and
concentrate on f-electron adatoms with large spin-orbital coupling. I
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 I trace the
difference to the exchange interaction between the adatom and the
tunneling electrons. The bilinear (Heisenberg) exchange J.s, assumed in
the spin model, implies that the magnetic quantum number m can only
change by zero or plus/minus one for single-electron scatterings. 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. Fernandez-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).
Host: Valerio Bellini e-mail: valerio.bellini@unimore.it