Spin Coupling and Orbital Angular Momentum Quenching in Free Iron Clusters

M. Niemeyer, K. Hirsch, V. Zamudio-Bayer, A. Langenberg, M. Vogel, M. Kossick, C. Ebrecht, K. Egashira, A. Terasaki, T. Möller, B. v. Issendorff, and J. T. Lau

Phys. Rev. Lett. 108, 057201 – Published 30 January 2012

Abstract

Magnetic spin and orbital moments of size-selected free iron cluster ions ${Fe}_{n}^{+}$ ( $n = 3 - 20$ ) have been determined via x-ray magnetic circular dichroism spectroscopy. Iron atoms within the clusters exhibit ferromagnetic coupling except for $F e_{13}^{+}$ , where the central atom is coupled antiferromagnetically to the atoms in the surrounding shell. Even in very small clusters, the orbital magnetic moment is strongly quenched and reduced to 5%–25% of its atomic value while the spin magnetic moment remains at 60%–90%. This demonstrates that the formation of bonds quenches orbital angular momenta in homonuclear iron clusters already for coordination numbers much smaller than those of the bulk.

Received 16 October 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.057201

Authors & Affiliations

M. Niemeyer^1,2, K. Hirsch^1,2, V. Zamudio-Bayer^1,2, A. Langenberg^1,2, M. Vogel¹, M. Kossick^1,2, C. Ebrecht^1,2, K. Egashira³, A. Terasaki^4,5, T. Möller², B. v. Issendorff⁶, and J. T. Lau^1,*

¹Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
²Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
³East Tokyo Laboratory, Genesis Research Institute, Inc., 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
⁴Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
⁵Department of Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
⁶Fakultät für Physik, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany

^*tobias.lau@helmholtz-berlin.de

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Vol. 108, Iss. 5 — 3 February 2012

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