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Maximum Spin Polarization in Chromium Dimer Cations as Demonstrated by X‐ray Magnetic Circular Dichroism Spectroscopy |
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| Authors: | Dr. Vicente Zamudio‐Bayer Dr. Konstantin Hirsch Dr. Andreas Langenberg Dipl.‐Phys. Markus Niemeyer Dr. Marlene Vogel Dr. Arkadiusz Ławicki Prof. Dr. Akira Terasaki Dr. J. Tobias Lau Prof. Dr. Bernd von Issendorff |
| Affiliation: | 1. Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz‐Zentrum Berlin für Materialien und Energie GmbH, Albert‐Einstein‐Strasse 15, 12489 Berlin (Germany);2. Institut für Optik und Atomare Physik, Technische Universit?t Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany);3. Department of Chemistry, Kyushu University, 6‐10‐1 Hakozaki, Higashi‐ku, Fukuoka 812‐8581 (Japan);4. Physikalisches Institut, Universit?t Freiburg, Stefan‐Meier‐Strasse 21, 79104 Freiburg (Germany) |
| Abstract: | X‐ray magnetic circular dichroism spectroscopy has been used to characterize the electronic structure and magnetic moment of Cr2+. Our results indicate that the removal of a single electron from the 4sσg bonding orbital of Cr2 drastically changes the preferred coupling of the 3d electronic spins. While the neutral molecule has a zero‐spin ground state with a very short bond length, the molecular cation exhibits a ferromagnetically coupled ground state with the highest possible spin of S=11/2, and almost twice the bond length of the neutral molecule. This spin configuration can be interpreted as a result of indirect exchange coupling between the 3d electrons of the two atoms that is mediated by the single 4s electron through a strong intraatomic 3d‐4s exchange interaction. Our finding allows an estimate of the relative energies of two states that are often discussed as ground‐state candidates, the ferromagnetically coupled 12Σ and the low‐spin 2Σ state. |
| Keywords: | chromium exchange interactions ion trap magnetic properties X‐ray absorption spectroscopy |