Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 88: Electronic structure II

O 88.7: Talk

Friday, March 30, 2012, 12:00–12:15, MA 043

Extremely short mean free path of electrons in lanthanides — •Karen Zumbrägel, Anke B. Schmidt, and Markus Donath — Physikalisches Institut, WWU Münster

The probing depth of electron spectroscopies is determined by the mean free path of electrons within the investigated material. Schönhense and Siegmann predicted a rule of thumb that for transition metals the electron mean free path for low energies is inversely proportional to the number of d holes [1]. This rule was confirmed for, e.g., Fe with 3 to 5 monolayers [2] and predicts an extremely short mean free path of less than 1 ML for Gd.

We performed overlayer experiments with gadolinium and terbium grown on tungsten. Applying inverse photoemission, we observed the decreasing intensity of tungsten bulk-state transitions as a function of the lanthanide film thickness. Thus we were able to determine the mean free path for low-energy electrons in gadolinium and terbium and confirm therewith the prediction of Schönhense and Siegmann.

[1]Schönhense and Siegmann, Ann. Phys. 2 (1993) 465

[2]Passek et al., J. Magn. Magn. Mat. 159 (1996) 103