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Tusche C, Ellguth M, Feyer V, Krasyuk A, Wiemann C, Henk J, Schneider CM, Kirschner J. Nonlocal electron correlations in an itinerant ferromagnet. Nat Commun 2018; 9:3727. [PMID: 30213929 PMCID: PMC6137183 DOI: 10.1038/s41467-018-05960-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 07/27/2018] [Indexed: 11/29/2022] Open
Abstract
Our understanding of the properties of ferromagnetic materials, widely used in spintronic devices, is fundamentally based on their electronic band structure. However, even for the most simple elemental ferromagnets, electron correlations are prevalent, requiring descriptions of their electronic structure beyond the simple picture of independent quasi-particles. Here, we give evidence that in itinerant ferromagnets like cobalt these electron correlations are of nonlocal origin, manifested in a complex self-energy Σσ(E,k) that disperses as function of spin σ, energy E, and momentum vector k. Together with one-step photoemission calculations, our experiments allow us to quantify the dispersive behaviour of the complex self-energy over the whole Brillouin zone. At the same time we observe regions of anomalously large "waterfall"-like band renormalization, previously only attributed to strong electron correlations in high-TC superconductors, making itinerant ferromagnets a paradigmatic test case for the interplay between band structure, magnetism, and many-body correlations.
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Affiliation(s)
- Christian Tusche
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany.
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany.
| | - Martin Ellguth
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Vitaliy Feyer
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Alexander Krasyuk
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Carsten Wiemann
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Jürgen Henk
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle, Germany
| | - Claus M Schneider
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Jürgen Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle, Germany
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Lu Y, Sun T, Zhang P, Zhang P, Zhang DB, Wentzcovitch RM. Premelting hcp to bcc Transition in Beryllium. PHYSICAL REVIEW LETTERS 2017; 118:145702. [PMID: 28430478 DOI: 10.1103/physrevlett.118.145702] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Indexed: 06/07/2023]
Abstract
Beryllium (Be) is an important material with wide applications ranging from aerospace components to x-ray equipment. Yet a precise understanding of its phase diagram remains elusive. We have investigated the phase stability of Be using a recently developed hybrid free energy computation method that accounts for anharmonic effects by invoking phonon quasiparticles. We find that the hcp → bcc transition occurs near the melting curve at 0<P<11 GPa with a positive Clapeyron slope of 41±4 K/GPa, which is more consistent with recent experimental measurements. This work also demonstrates the validity of this theoretical framework based on the phonon quasiparticle to study the structural stability and phase transitions in strongly anharmonic materials.
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Affiliation(s)
- Y Lu
- Beijing Computational Science Research Center, Beijing 100193, China
| | - T Sun
- Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
| | - P Zhang
- Beijing Computational Science Research Center, Beijing 100193, China
- Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
| | - D-B Zhang
- Beijing Computational Science Research Center, Beijing 100193, China
| | - R M Wentzcovitch
- Materials Science and Engineering, Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA and Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
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