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Hirsch K, Zamudio-Bayer V, Langenberg A, Niemeyer M, Langbehn B, Möller T, Terasaki A, Issendorff BV, Lau JT. Magnetic moments of chromium-doped gold clusters: the Anderson impurity model in finite systems. PHYSICAL REVIEW LETTERS 2015; 114:087202. [PMID: 25768776 DOI: 10.1103/physrevlett.114.087202] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Indexed: 05/26/2023]
Abstract
The magnetic moment of a single impurity atom in a finite free electron gas is studied in a combined x-ray magnetic circular dichroism spectroscopy, charge transfer multiplet calculation, and density functional theory study of size-selected free chromium-doped gold clusters. The observed size dependence of the local magnetic moment can be understood as a transition from a local moment to a mixed valence regime. This shows that the Anderson impurity model essentially describes finite systems even though the discrete density of states introduces a significant deviation from a bulk metal, and the free electron gas is only formed by less than 10 electrons. Electronic shell closure in the gold host minimizes the interaction of localized impurity states with the confined free electron gas and preserves the magnetic moment of 5 μ_{B} fully in CrAu_{2}^{+} and almost fully in CrAu_{6}^{+}. Even for open-shell species, large local moments are observed that scale with the energy gap of the gold cluster. This indicates that an energy gap in the free electron gas stabilizes the local magnetic moment of the impurity atom.
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Affiliation(s)
- K Hirsch
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - V Zamudio-Bayer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A Langenberg
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - M Niemeyer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - B Langbehn
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - T Möller
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - A Terasaki
- Cluster Research Laboratory, Toyota Technological Institute, 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
- Department of Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - B V Issendorff
- Physikalisches Institut, Universität Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
| | - J T Lau
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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Bezerra-Neto MM, Ribeiro MS, Sanyal B, Bergman A, Muniz RB, Eriksson O, Klautau AB. Complex magnetic structure of clusters and chains of Ni and Fe on Pt(111). Sci Rep 2013; 3:3054. [PMID: 24165828 PMCID: PMC3810666 DOI: 10.1038/srep03054] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 09/13/2013] [Indexed: 11/30/2022] Open
Abstract
We present an approach to control the magnetic structure of adatoms adsorbed on a substrate having a high magnetic susceptibility. Using finite Ni-Pt and Fe-Pt nanowires and nanostructures on Pt(111) surfaces, our ab initio results show that it is possible to tune the exchange interaction and magnetic configuration of magnetic adatoms (Fe or Ni) by introducing different numbers of Pt atoms to link them, or by including edge effects. The exchange interaction between Ni (or Fe) adatoms on Pt(111) can be considerably increased by introducing Pt chains to link them. The magnetic ordering can be regulated allowing for ferromagnetic or antiferromagnetic configurations. Noncollinear magnetic alignments can also be stabilized by changing the number of Pt-mediated atoms. An Fe-Pt triangularly-shaped nanostructure adsorbed on Pt(111) shows the most complex magnetic structure of the systems considered here: a spin-spiral type of magnetic order that changes its propagation direction at the triangle vertices.
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Ataç D, Gang T, Yilmaz MD, Bose SK, Lenferink ATM, Otto C, de Jong MP, Huskens J, van der Wiel WG. Tuning the Kondo effect in thin Au films by depositing a thin layer of Au on molecular spin-dopants. NANOTECHNOLOGY 2013; 24:375204. [PMID: 23975183 DOI: 10.1088/0957-4484/24/37/375204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report on the tuning of the Kondo effect in thin Au films containing a monolayer of cobalt(II) terpyridine complexes by altering the ligand structure around the Co(2+) ions by depositing a thin Au capping layer on top of the monolayer on Au by magnetron sputtering (more energetic) and e-beam evaporation (softer). We show that the Kondo effect is slightly enhanced with respect to that of the uncapped film when the cap is deposited by evaporation, and significantly enhanced when magnetron sputtering is used. The Kondo temperature (TK) increases from 3 to 4.2/6.2 K for the evaporated/sputtered caps. X-ray absorption spectroscopy and surface-enhanced Raman spectroscopy investigation showed that the organic ligands remain intact upon Au e-beam evaporation; however, sputtering inflicts significant change in the Co(2+) electronic environment. The location of the monolayer-on the surface or embedded in the film-has a small effect. However, the damage of Co-N bonds induced by sputtering has a drastic effect on the increase of the impurity-electron interaction. This opens up the way for tuning of the magnetic impurity states, e.g. spin quantum number, binding energy with respect to the host Fermi energy, and overlap via the ligand structure around the ions.
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Affiliation(s)
- D Ataç
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
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Gu B, Gan JY, Bulut N, Ziman T, Guo GY, Nagaosa N, Maekawa S. Quantum renormalization of the spin Hall effect. PHYSICAL REVIEW LETTERS 2010; 105:086401. [PMID: 20868117 DOI: 10.1103/physrevlett.105.086401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Indexed: 05/29/2023]
Abstract
By quantum Monte Carlo simulation of a realistic multiorbital Anderson impurity model, we study the spin-orbit interaction (SOI) of an Fe impurity in Au host metal. We show, for the first time, that the SOI is strongly renormalized by the quantum spin fluctuation. Based on this mechanism, we can explain why the gigantic spin Hall effect in Au with Fe impurities was observed in recent experiments, while it is not visible in the anomalous Hall effect. In addition, we show that the SOI is strongly renormalized by the Coulomb correlation U. Based on this picture, we can explain past discrepancies in the calculated orbital angular momenta for an Fe impurity in an Au host.
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Affiliation(s)
- Bo Gu
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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Klautau AB, Socolovsky LM, Nogueira RN, Petrilli HM. Hyperfine and magnetic properties of Fe-Cu clusters and Fe precipitates embedded in a Cu matrix. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:506001. [PMID: 21836226 DOI: 10.1088/0953-8984/21/50/506001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Using the first-principles real-space linear muffin-tin orbital method within the atomic sphere approximation (RS-LMTO-ASA) we study hyperfine and local magnetic properties of substituted pure Fe and Fe-Cu clusters in an fcc Cu matrix. Spin and orbital contributions to magnetic moments, hyperfine fields and the Mössbauer isomer shifts at the Fe sites in Fe precipitates and Fe-Cu alloy clusters of sizes up to 60 Fe atoms embedded in the Cu matrix are calculated and the influence of the local environment on these properties is discussed.
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Affiliation(s)
- A B Klautau
- Faculdade de Física, Universidade Federal do Pará, 66075-110, Belém, PA, Brazil
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Costi TA, Bergqvist L, Weichselbaum A, von Delft J, Micklitz T, Rosch A, Mavropoulos P, Dederichs PH, Mallet F, Saminadayar L, Bäuerle C. Kondo decoherence: finding the right spin model for iron impurities in gold and silver. PHYSICAL REVIEW LETTERS 2009; 102:056802. [PMID: 19257534 DOI: 10.1103/physrevlett.102.056802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Indexed: 05/27/2023]
Abstract
We exploit the decoherence of electrons due to magnetic impurities, studied via weak localization, to resolve a long-standing question concerning the classic Kondo systems of Fe impurities in the noble metals gold and silver: which Kondo-type model yields a realistic description of the relevant multiple bands, spin, and orbital degrees of freedom? Previous studies suggest a fully screened spin S Kondo model, but the value of S remained ambiguous. We perform density functional theory calculations that suggest S=3/2. We also compare previous and new measurements of both the resistivity and decoherence rate in quasi-one-dimensional wires to numerical renormalization group predictions for S=1/2, 1, and 3/2, finding excellent agreement for S=3/2.
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Affiliation(s)
- T A Costi
- Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany
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