1
|
Elnaggar H, Sainctavit P, Juhin A, Lafuerza S, Wilhelm F, Rogalev A, Arrio MA, Brouder C, van der Linden M, Kakol Z, Sikora M, Haverkort MW, Glatzel P, de Groot FMF. Noncollinear Ordering of the Orbital Magnetic Moments in Magnetite. PHYSICAL REVIEW LETTERS 2019; 123:207201. [PMID: 31809079 DOI: 10.1103/physrevlett.123.207201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 10/02/2019] [Indexed: 05/22/2023]
Abstract
The magnitude of the orbital magnetic moment and its role as a trigger of the Verwey transition in the prototypical Mott insulator, magnetite, remain contentious. Using 1s2p resonant inelastic x-ray scattering angle distribution (RIXS-AD), we prove the existence of noncollinear orbital magnetic ordering and infer the presence of dynamical distortion creating a polaronic precursor for the metal to insulator transition. These conclusions are based on a subtle angular shift of the RIXS-AD spectral intensity as a function of the magnetic field orientation. Theoretical simulations show that these results are only consistent with noncollinear magnetic orbital ordering. To further support these claims we perform Fe K-edge x-ray magnetic circular dichroism in order to quantify the Fe average orbital magnetic moment.
Collapse
Affiliation(s)
- H Elnaggar
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CA Utrecht, The Netherlands
| | - Ph Sainctavit
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - A Juhin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - S Lafuerza
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - F Wilhelm
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - A Rogalev
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - M-A Arrio
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - Ch Brouder
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, MNHN, UMR7590, 75252 Paris Cedex 05, France
| | - M van der Linden
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CA Utrecht, The Netherlands
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - Z Kakol
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland
| | - M Sikora
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland
| | - M W Haverkort
- Institut für Theoritiche Physik, Universität Heidelberg, Philosophenweg 19, 69120 Heidelberg, Germany
| | - P Glatzel
- European Synchrotron Radiation Facility, CS40220, F-38043 Grenoble Cedex 9, France
| | - F M F de Groot
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CA Utrecht, The Netherlands
| |
Collapse
|
2
|
Kukreja R, Hua N, Ruby J, Barbour A, Hu W, Mazzoli C, Wilkins S, Fullerton EE, Shpyrko OG. Orbital Domain Dynamics in Magnetite below the Verwey Transition. PHYSICAL REVIEW LETTERS 2018; 121:177601. [PMID: 30411967 DOI: 10.1103/physrevlett.121.177601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 07/06/2018] [Indexed: 05/27/2023]
Abstract
The metal-insulator phase transition in magnetite, known as the Verwey transition, is characterized by a charge-orbital ordering and a lattice transformation from a cubic to monoclinic structure. We use x-ray photon correlation spectroscopy to investigate the dynamics of this charge-orbitally ordered insulating phase undergoing the insulator-to-metal transition. By tuning to the Fe L_{3} edge at the (001/2) superlattice peak, we probe the evolution of the Fe t_{2g} orbitally ordered domains present in the low temperature insulating phase and forbidden in the high temperature metallic phase. We observe two distinct regimes below the Verwey transition. In the first regime, magnetite follows an Arrhenius behavior and the characteristic timescale for orbital fluctuations decreases as the temperature increases. In the second regime, magnetite phase separates into metallic and insulating domains, and the kinetics of the phase transition is dictated by metallic-insulating interfacial boundary conditions.
Collapse
Affiliation(s)
- Roopali Kukreja
- Department of Physics, University of California, San Diego, La Jolla, California, 92093, USA
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California, 92093, USA
- Department of Materials Science Engineering, University of California, Davis, Davis, California, 95616, USA
| | - Nelson Hua
- Department of Physics, University of California, San Diego, La Jolla, California, 92093, USA
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California, 92093, USA
| | - Joshua Ruby
- Department of Physics, University of California, San Diego, La Jolla, California, 92093, USA
| | - Andi Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Wen Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Claudio Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Stuart Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California, 92093, USA
| | - Oleg G Shpyrko
- Department of Physics, University of California, San Diego, La Jolla, California, 92093, USA
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California, 92093, USA
| |
Collapse
|
3
|
Pontius N, Beye M, Trabant C, Mitzner R, Sorgenfrei F, Kachel T, Wöstmann M, Roling S, Zacharias H, Ivanov R, Treusch R, Buchholz M, Metcalf P, Schüßler-Langeheine C, Föhlisch A. Probing the non-equilibrium transient state in magnetite by a jitter-free two-color X-ray pump and X-ray probe experiment. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:054501. [PMID: 30310825 PMCID: PMC6158032 DOI: 10.1063/1.5042847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/23/2018] [Indexed: 06/08/2023]
Abstract
We present a general experimental concept for jitter-free pump and probe experiments at free electron lasers. By generating pump and probe pulse from one and the same X-ray pulse using an optical split-and-delay unit, we obtain a temporal resolution that is limited only by the X-ray pulse lengths. In a two-color X-ray pump and X-ray probe experiment with sub 70 fs temporal resolution, we selectively probe the response of orbital and charge degree of freedom in the prototypical functional oxide magnetite after photoexcitation. We find electronic order to be quenched on a time scale of (30 ± 30) fs and hence most likely faster than what is to be expected for any lattice dynamics. Our experimental result hints to the formation of a short lived transient state with decoupled electronic and lattice degree of freedom in magnetite. The excitation and relaxation mechanism for X-ray pumping is discussed within a simple model leading to the conclusion that within the first 10 fs the original photoexcitation decays into low-energy electronic excitations comparable to what is achieved by optical pump pulse excitation. Our findings show on which time scales dynamical decoupling of degrees of freedom in functional oxides can be expected and how to probe this selectively with soft X-ray pulses. Results can be expected to provide crucial information for theories for ultrafast behavior of materials and help to develop concepts for novel switching devices.
Collapse
Affiliation(s)
- N Pontius
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - M Beye
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - C Trabant
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - R Mitzner
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - F Sorgenfrei
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - T Kachel
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - M Wöstmann
- WWU Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - S Roling
- WWU Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - H Zacharias
- WWU Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
| | - R Ivanov
- Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany
| | - R Treusch
- Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany
| | - M Buchholz
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - P Metcalf
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - C Schüßler-Langeheine
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - A Föhlisch
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| |
Collapse
|
4
|
Macke S, Hamann-Borrero JE, Green RJ, Keimer B, Sawatzky GA, Haverkort MW. Dynamical Effects in Resonant X-Ray Diffraction. PHYSICAL REVIEW LETTERS 2016; 117:115501. [PMID: 27661698 DOI: 10.1103/physrevlett.117.115501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 06/06/2023]
Abstract
Using resonant magnetic diffraction at the Ni L_{2,3} edge in a LaNiO_{3} superlattice, we show that dynamical effects beyond the standard kinematic approximation can drastically modify the resonant scattering cross section. In particular, the combination of extinction and refraction convert maxima to minima in the azimuthal-angle dependence of the diffracted intensity, which is commonly used to determine orbital and magnetic structures by resonant x-ray diffraction. We provide a comprehensive theoretical description of these effects by numerically solving Maxwell's equations in three dimensions. The understanding and description of dynamical diffraction enhances the capabilities of resonant x-ray scattering as a probe of electronic ordering phenomena in solids.
Collapse
Affiliation(s)
- S Macke
- Quantum Matter Institute, Physics and Astronomy Department, The Brimacombe Building, 2355 East Mall, Vancouver V6T 1Z4, Canada
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - J E Hamann-Borrero
- Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrae 20, 01069 Dresden, Germany
| | - R J Green
- Quantum Matter Institute, Physics and Astronomy Department, The Brimacombe Building, 2355 East Mall, Vancouver V6T 1Z4, Canada
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - B Keimer
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - G A Sawatzky
- Quantum Matter Institute, Physics and Astronomy Department, The Brimacombe Building, 2355 East Mall, Vancouver V6T 1Z4, Canada
| | - M W Haverkort
- Quantum Matter Institute, Physics and Astronomy Department, The Brimacombe Building, 2355 East Mall, Vancouver V6T 1Z4, Canada
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| |
Collapse
|
5
|
Abstract
We demonstrate the microscopic role of oxygen vacancies spatially confined within nanometer inter-spacing (about 1 nm) in BiFeO3, using resonant soft X-ray scattering techniques and soft X-ray spectroscopy measurements. Such vacancy confinements and total number of vacancy are controlled by substitution of Ca(2+) for Bi(3+) cation. We found that by increasing the substitution, the in-plane orbital bands of Fe(3+) cations are reconstructed without any redox reaction. It leads to a reduction of the hopping between Fe atoms, forming a localized valence band, in particular Fe 3d-electronic structure, around the Fermi level. This band localization causes to decrease the conductivity of the doped BiFeO3 system.
Collapse
|
6
|
Schmitz D, Schmitz-Antoniak C, Warland A, Darbandi M, Haldar S, Bhandary S, Eriksson O, Sanyal B, Wende H. The dipole moment of the spin density as a local indicator for phase transitions. Sci Rep 2014; 4:5760. [PMID: 25041757 PMCID: PMC4104392 DOI: 10.1038/srep05760] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/02/2014] [Indexed: 11/17/2022] Open
Abstract
The intra-atomic magnetic dipole moment - frequently called 〈Tz〉 term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe2+ and Fe3+ sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry.
Collapse
Affiliation(s)
- D Schmitz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - C Schmitz-Antoniak
- 1] Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany [2]
| | - A Warland
- Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany
| | - M Darbandi
- 1] Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany [2]
| | - S Haldar
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - S Bhandary
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - O Eriksson
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - B Sanyal
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120 Uppsala, Sweden
| | - H Wende
- Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany
| |
Collapse
|
7
|
de Jong S, Kukreja R, Trabant C, Pontius N, Chang CF, Kachel T, Beye M, Sorgenfrei F, Back CH, Bräuer B, Schlotter WF, Turner JJ, Krupin O, Doehler M, Zhu D, Hossain MA, Scherz AO, Fausti D, Novelli F, Esposito M, Lee WS, Chuang YD, Lu DH, Moore RG, Yi M, Trigo M, Kirchmann P, Pathey L, Golden MS, Buchholz M, Metcalf P, Parmigiani F, Wurth W, Föhlisch A, Schüßler-Langeheine C, Dürr HA. Speed limit of the insulator-metal transition in magnetite. NATURE MATERIALS 2013; 12:882-6. [PMID: 23892787 DOI: 10.1038/nmat3718] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 06/24/2013] [Indexed: 05/19/2023]
Abstract
As the oldest known magnetic material, magnetite (Fe3O4) has fascinated mankind for millennia. As the first oxide in which a relationship between electrical conductivity and fluctuating/localized electronic order was shown, magnetite represents a model system for understanding correlated oxides in general. Nevertheless, the exact mechanism of the insulator-metal, or Verwey, transition has long remained inaccessible. Recently, three-Fe-site lattice distortions called trimerons were identified as the characteristic building blocks of the low-temperature insulating electronically ordered phase. Here we investigate the Verwey transition with pump-probe X-ray diffraction and optical reflectivity techniques, and show how trimerons become mobile across the insulator-metal transition. We find this to be a two-step process. After an initial 300 fs destruction of individual trimerons, phase separation occurs on a 1.5±0.2 ps timescale to yield residual insulating and metallic regions. This work establishes the speed limit for switching in future oxide electronics.
Collapse
Affiliation(s)
- S de Jong
- 1] Stanford Institute for Energy and Materials Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2]
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Müller L, Gutt C, Pfau B, Schaffert S, Geilhufe J, Büttner F, Mohanty J, Flewett S, Treusch R, Düsterer S, Redlin H, Al-Shemmary A, Hille M, Kobs A, Frömter R, Oepen HP, Ziaja B, Medvedev N, Son SK, Thiele R, Santra R, Vodungbo B, Lüning J, Eisebitt S, Grübel G. Breakdown of the x-ray resonant magnetic scattering signal during intense pulses of extreme ultraviolet free-electron-laser radiation. PHYSICAL REVIEW LETTERS 2013; 110:234801. [PMID: 25167501 DOI: 10.1103/physrevlett.110.234801] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Indexed: 05/23/2023]
Abstract
We present results of single-shot resonant magnetic scattering experiments of Co/Pt multilayer systems using 100 fs long ultraintense pulses from an extreme ultraviolet (XUV) free-electron laser. An x-ray-induced breakdown of the resonant magnetic scattering channel during the pulse duration is observed at fluences of 5 J/cm(2). Simultaneously, the speckle contrast of the high-fluence scattering pattern is significantly reduced. We performed simulations of the nonequilibrium evolution of the Co/Pt multilayer system during the XUV pulse duration. We find that the electronic state of the sample is strongly perturbed during the first few femtoseconds of exposure leading to an ultrafast quenching of the resonant magnetic scattering mechanism.
Collapse
Affiliation(s)
- L Müller
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - C Gutt
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - B Pfau
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - S Schaffert
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - J Geilhufe
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - F Büttner
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - J Mohanty
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - S Flewett
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - R Treusch
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - S Düsterer
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - H Redlin
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - A Al-Shemmary
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - M Hille
- Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - A Kobs
- Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - R Frömter
- Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - H P Oepen
- Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - B Ziaja
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany and Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany and Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow, Poland
| | - N Medvedev
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany
| | - S-K Son
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany
| | - R Thiele
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany
| | - R Santra
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany and Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany and I. Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - B Vodungbo
- Laboratoire de Chimie Physique Matière et Rayonnement-CNRS UMR 7614, Université Pierre et Marie Curie, 75005 Paris, France
| | - J Lüning
- Laboratoire de Chimie Physique Matière et Rayonnement-CNRS UMR 7614, Université Pierre et Marie Curie, 75005 Paris, France
| | - S Eisebitt
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany and Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - G Grübel
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany and The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| |
Collapse
|
9
|
Hoesch M, Piekarz P, Bosak A, Le Tacon M, Krisch M, Kozłowski A, Oleś AM, Parlinski K. Anharmonicity due to electron-phonon coupling in magnetite. PHYSICAL REVIEW LETTERS 2013; 110:207204. [PMID: 25167445 DOI: 10.1103/physrevlett.110.207204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Indexed: 05/22/2023]
Abstract
We present the results of inelastic x-ray scattering for magnetite and analyze the energies and widths of the phonon modes with different symmetries in a broad range of temperature 125 < T < 293 K. The phonon modes with X(4) and Δ(5) symmetries broaden in a nonlinear way with decreasing T when the Verwey transition is approached. It is found that the maxima of phonon widths occur away from high-symmetry points, which suggests the incommensurate character of critical fluctuations. Strong phonon anharmonicity induced by electron-phonon coupling is discovered by a combination of these experimental results with ab initio calculations which take into account local Coulomb interactions at Fe ions. It (i) explains observed anomalous phonon broadening and (ii) demonstrates that the Verwey transition is a cooperative phenomenon which involves a wide spectrum of phonons coupled to the electron charge fluctuations condensing in the low-symmetry phase.
Collapse
Affiliation(s)
- Moritz Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, Oxfordshire, United Kingdom
| | - Przemysław Piekarz
- Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, PL-31342 Kraków, Poland
| | - Alexey Bosak
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France
| | - Mathieu Le Tacon
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Michael Krisch
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France
| | - Andrzej Kozłowski
- Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Aleja Mickiewicza 30, PL-30059 Kraków, Poland
| | - Andrzej M Oleś
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany and Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland
| | - Krzysztof Parlinski
- Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, PL-31342 Kraków, Poland
| |
Collapse
|