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Zwiebler M, Di Gennaro E, Hamann-Borrero JE, Ritschel T, Green RJ, Sawatzky GA, Schierle E, Weschke E, Leo A, Granozio FM, Geck J. Transition from a uni- to a bimodal interfacial charge distribution in [Formula: see text]/[Formula: see text] upon cooling. Sci Rep 2020; 10:18359. [PMID: 33110119 PMCID: PMC7591581 DOI: 10.1038/s41598-020-74364-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/17/2020] [Indexed: 11/09/2022] Open
Abstract
We present a combined resonant soft X-ray reflectivity and electric transport study of [Formula: see text]/[Formula: see text] field effect devices. The depth profiles with atomic layer resolution that are obtained from the resonant reflectivity reveal a pronounced temperature dependence of the two-dimensional electron liquid at the [Formula: see text]/[Formula: see text] interface. At room temperature the corresponding electrons are located close to the interface, extending down to 4 unit cells into the [Formula: see text] substrate. Upon cooling, however, these interface electrons assume a bimodal depth distribution: They spread out deeper into the [Formula: see text] and split into two distinct parts, namely one close to the interface with a thickness of about 4 unit cells and another centered around 9 unit cells from the interface. The results are consistent with theoretical predictions based on oxygen vacancies at the surface of the [Formula: see text] film and support the notion of a complex interplay between structural and electronic degrees of freedom.
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Affiliation(s)
- M. Zwiebler
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - E. Di Gennaro
- Dipartimento di Fisica “E. Pancini”, Università di Napoli “Federico II”, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
- CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
| | - J. E. Hamann-Borrero
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - T. Ritschel
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - R. J. Green
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, V6T 1Z1 Canada
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, S7N 5E2 Canada
| | - G. A. Sawatzky
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, V6T 1Z1 Canada
| | - E. Schierle
- Helmholtz-Zentrum Berlin, BESSY, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - E. Weschke
- Helmholtz-Zentrum Berlin, BESSY, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - A. Leo
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, Fisciano, Italy
- CNR-SPIN, Campus di Fisciano-Salerno, Fisciano, Italy
| | - F. Miletto Granozio
- CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
| | - J. Geck
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
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2
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Donnerer C, Rahn MC, Schierle E, Perry RS, Veiga LSI, Nisbet G, Collins SP, Prabhakaran D, Boothroyd AT, McMorrow DF. Selective probing of magnetic order on Tb and Ir sites in stuffed Tb 2Ir 2O 7 using resonant x-ray scattering. J Phys Condens Matter 2019; 31:344001. [PMID: 31096195 DOI: 10.1088/1361-648x/ab2217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the magnetic structure of the 'stuffed' (Tb-rich) pyrochlore iridate Tb2+x Ir2-x O7-y (x ∼ 0.18), using resonant elastic x-ray scattering (REXS). In order to disentangle contributions from Tb and Ir magnetic sublattices, experiments were performed at the Ir L 3 and Tb M 5 edges, which provide selective sensitivity to Ir 5d and Tb 4f magnetic moments, respectively. At the Ir L 3 edge, we found the onset of long-range [Formula: see text] magnetic order below [Formula: see text] K, consistent with the expected signal of all-in all-out (AIAO) magnetic order. Using a single-ion model to calculate REXS cross-sections, we estimate an ordered magnetic moment of [Formula: see text] at 5 K. At the Tb M 5 edge, long-range [Formula: see text] magnetic order appeared below ∼[Formula: see text] K, also consistent with an AIAO magnetic structure on the Tb site. Additional insight into the magnetism of the Tb sublattice is gleaned from measurements at the M 5 edge in applied magnetic fields up to 6 T, which is found to completely suppress the Tb AIAO magnetic order. In zero applied field, the observed gradual onset of the Tb sublattice magnetisation with temperature suggests that it is induced by the magnetic order on the Ir site. The persistence of AIAO magnetic order, despite the greatly reduced ordering temperature and moment size compared to stoichiometric Tb2Ir2O7, for which [Formula: see text] K and [Formula: see text], indicates that stuffing could be a viable means of tuning the strength of electronic correlations, thereby potentially offering a new strategy to achieve topologically non-trivial band crossings in pyrochlore iridates.
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Affiliation(s)
- C Donnerer
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
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3
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Hamann-Borrero JE, Macke S, Gray B, Kareev M, Schierle E, Partzsch S, Zwiebler M, Treske U, Koitzsch A, Büchner B, Freeland JW, Chakhalian J, Geck J. Site-selective spectroscopy with depth resolution using resonant x-ray reflectometry. Sci Rep 2017; 7:13792. [PMID: 29061996 PMCID: PMC5653850 DOI: 10.1038/s41598-017-12642-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 09/13/2017] [Indexed: 11/21/2022] Open
Abstract
Combining dissimilar transition metal oxides (TMOs) into artificial heterostructures enables to create electronic interface systems with new electronic properties that do not exist in bulk. A detailed understanding of how such interfaces can be used to tailor physical properties requires characterization techniques capable to yield interface sensitive spectroscopic information with monolayer resolution. In this regard resonant x-ray reflectivity (RXR) provides a unique experimental tool to achieve exactly this. It yields the element specific electronic depth profiles in a non-destructive manner. Here, using a YBa2Cu3O7−δ (YBCO) thin film, we demonstrate that RXR is further capable to deliver site selectivity. By applying a new analysis scheme to RXR, which takes the atomic structure of the material into account, together with information of the local charge anisotropy of the resonant ions, we obtained spectroscopic information from the different Cu sites (e.g., chain and plane) throughout the film profile. While most of the film behaves bulk-like, we observe that the Cu-chains at the surface show characteristics of electron doping, whereas the Cu-planes closest to the surface exhibit an orbital reconstruction similar to that observed at La1−xCaxMnO3/YBCO interfaces.
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Affiliation(s)
- J E Hamann-Borrero
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01171, Dresden, Germany.
| | - S Macke
- Quantum Matter Institute, University of British Columbia, 2355 East Mall, Vancouver, V6T 1Z4, Canada.,Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569, Stuttgart, Germany
| | - B Gray
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, 70701, USA
| | - M Kareev
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey, 08854, USA
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, D-12489, Berlin, Germany
| | - S Partzsch
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01171, Dresden, Germany
| | - M Zwiebler
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01171, Dresden, Germany
| | - U Treske
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01171, Dresden, Germany
| | - A Koitzsch
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01171, Dresden, Germany
| | - B Büchner
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01171, Dresden, Germany.,Institut für Festkörper- und Materialphysik, TU Dresden, D-01062, Dresden, Germany
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - J Chakhalian
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey, 08854, USA
| | - J Geck
- Institut für Festkörper- und Materialphysik, TU Dresden, D-01062, Dresden, Germany.
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4
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Bluschke M, Frano A, Schierle E, Minola M, Hepting M, Christiani G, Logvenov G, Weschke E, Benckiser E, Keimer B. Transfer of Magnetic Order and Anisotropy through Epitaxial Integration of 3d and 4f Spin Systems. Phys Rev Lett 2017; 118:207203. [PMID: 28581806 DOI: 10.1103/physrevlett.118.207203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Indexed: 06/07/2023]
Abstract
Resonant x-ray scattering at the Dy M_{5} and Ni L_{3} absorption edges was used to probe the temperature and magnetic field dependence of magnetic order in epitaxial LaNiO_{3}-DyScO_{3} superlattices. For superlattices with 2 unit cell thick LaNiO_{3} layers, a commensurate spiral state develops in the Ni spin system below 100 K. Upon cooling below T_{ind}=18 K, Dy-Ni exchange interactions across the LaNiO_{3}-DyScO_{3} interfaces induce collinear magnetic order of interfacial Dy moments as well as a reorientation of the Ni spins to a direction dictated by the strong magnetocrystalline anisotropy of Dy. This transition is reversible by an external magnetic field of 3 T. Tailored exchange interactions between rare-earth and transition-metal ions thus open up new perspectives for the manipulation of spin structures in metal-oxide heterostructures and devices.
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Affiliation(s)
- M Bluschke
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - A Frano
- Department of Physics, University of California, Berkeley, California 94720, USA and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - M Minola
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - M Hepting
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - G Christiani
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - G Logvenov
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - E Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - E Benckiser
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - B Keimer
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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5
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Frano A, Blanco-Canosa S, Schierle E, Lu Y, Wu M, Bluschke M, Minola M, Christiani G, Habermeier HU, Logvenov G, Wang Y, van Aken PA, Benckiser E, Weschke E, Le Tacon M, Keimer B. Long-range charge-density-wave proximity effect at cuprate/manganate interfaces. Nat Mater 2016; 15:831-834. [PMID: 27322824 DOI: 10.1038/nmat4682] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/25/2016] [Indexed: 06/06/2023]
Abstract
The interplay between charge density waves (CDWs) and high-temperature superconductivity is currently under intense investigation. Experimental research on this issue is difficult because CDW formation in bulk copper oxides is strongly influenced by random disorder, and a long-range-ordered CDW state in high magnetic fields is difficult to access with spectroscopic and diffraction probes. Here we use resonant X-ray scattering in zero magnetic field to show that interfaces with the metallic ferromagnet La2/3Ca1/3MnO3 greatly enhance CDW formation in the optimally doped high-temperature superconductor YBa2Cu3O6+δ (δ ∼ 1), and that this effect persists over several tens of nanometres. The wavevector of the incommensurate CDW serves as an internal calibration standard of the charge carrier concentration, which allows us to rule out any significant influence of oxygen non-stoichiometry, and to attribute the observed phenomenon to a genuine electronic proximity effect. Long-range proximity effects induced by heterointerfaces thus offer a powerful method to stabilize the charge-density-wave state in the cuprates and, more generally, to manipulate the interplay between different collective phenomena in metal oxides.
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Affiliation(s)
- A Frano
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - S Blanco-Canosa
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Y Lu
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - M Wu
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - M Bluschke
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - M Minola
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - G Christiani
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - H U Habermeier
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - G Logvenov
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Y Wang
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - P A van Aken
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - E Benckiser
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - E Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - M Le Tacon
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - B Keimer
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
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6
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Grisolia M, Varignon J, Sanchez-Santolino G, Arora A, Valencia S, Varela M, Abrudan R, Weschke E, Schierle E, Rault J, Rueff JP, Barthélémy A, Santamaria J, Bibes M. Hybridization-controlled charge transfer and induced magnetism at correlated oxide interfaces. Nat Phys 2016; 12:484-492. [PMID: 27158255 PMCID: PMC4856211 DOI: 10.1038/nphys3627] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 12/04/2015] [Indexed: 05/22/2023]
Abstract
At interfaces between conventional materials, band bending and alignment are classically controlled by differences in electrochemical potential. Applying this concept to oxides in which interfaces can be polar and cations may adopt a mixed valence has led to the discovery of novel two-dimensional states between simple band insulators such as LaAlO3 and SrTiO3. However, many oxides have a more complex electronic structure, with charge, orbital and/or spin orders arising from strong Coulomb interactions between transition metal and oxygen ions. Such electronic correlations offer a rich playground to engineer functional interfaces but their compatibility with the classical band alignment picture remains an open question. Here we show that beyond differences in electron affinities and polar effects, a key parameter determining charge transfer at correlated oxide interfaces is the energy required to alter the covalence of the metal-oxygen bond. Using the perovskite nickelate (RNiO3) family as a template, we probe charge reconstruction at interfaces with gadolinium titanate GdTiO3. X-ray absorption spectroscopy shows that the charge transfer is thwarted by hybridization effects tuned by the rare-earth (R) size. Charge transfer results in an induced ferromagnetic-like state in the nickelate, exemplifying the potential of correlated interfaces to design novel phases. Further, our work clarifies strategies to engineer two-dimensional systems through the control of both doping and covalence.
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Affiliation(s)
- M.N. Grisolia
- Unité Mixte de Physique CNRS/Thales, 1 avenue A. Fresnel, 91767 Palaiseau, France, and Université Paris-Sud, 91405 Orsay, France
| | - J. Varignon
- Unité Mixte de Physique CNRS/Thales, 1 avenue A. Fresnel, 91767 Palaiseau, France, and Université Paris-Sud, 91405 Orsay, France
| | - G. Sanchez-Santolino
- GFMC, Departamento Física Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain, and Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense de Madrid, Sor Juana Inés de la Cruz, 3, 28049 Madrid, Spain
| | - A. Arora
- Helmholtz-Zentrum Berlin für Materialen & Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - S. Valencia
- Helmholtz-Zentrum Berlin für Materialen & Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - M. Varela
- GFMC, Departamento Física Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain, and Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense de Madrid, Sor Juana Inés de la Cruz, 3, 28049 Madrid, Spain
- Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - R. Abrudan
- Helmholtz-Zentrum Berlin für Materialen & Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
- Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - E. Weschke
- Helmholtz-Zentrum Berlin für Materialen & Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - E. Schierle
- Helmholtz-Zentrum Berlin für Materialen & Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - J.E. Rault
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - J.-P. Rueff
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - A. Barthélémy
- Unité Mixte de Physique CNRS/Thales, 1 avenue A. Fresnel, 91767 Palaiseau, France, and Université Paris-Sud, 91405 Orsay, France
| | - J. Santamaria
- GFMC, Departamento Física Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain, and Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense de Madrid, Sor Juana Inés de la Cruz, 3, 28049 Madrid, Spain
| | - M. Bibes
- Unité Mixte de Physique CNRS/Thales, 1 avenue A. Fresnel, 91767 Palaiseau, France, and Université Paris-Sud, 91405 Orsay, France
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7
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Sánchez-Barriga J, Varykhalov A, Springholz G, Steiner H, Kirchschlager R, Bauer G, Caha O, Schierle E, Weschke E, Ünal AA, Valencia S, Dunst M, Braun J, Ebert H, Minár J, Golias E, Yashina LV, Ney A, Holý V, Rader O. Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi(1-x)Mn(x))2Se3. Nat Commun 2016; 7:10559. [PMID: 26892831 PMCID: PMC4762886 DOI: 10.1038/ncomms10559] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 12/26/2015] [Indexed: 12/04/2022] Open
Abstract
Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi1−xMnx)2Se3 is a prototypical magnetic topological insulator with a pronounced surface band gap of ∼100 meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection. Doping a topological insulator with magnetic impurities is expected to induce ferromagnetism and open a band gap in its surface states. Here, the authors study Mn-doped Bi2Se3, finding a mechanism for band gap opening in topologically-protected surface states which is not of magnetic origin.
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Affiliation(s)
- J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - G Springholz
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - H Steiner
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - R Kirchschlager
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - G Bauer
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - O Caha
- Department of Condensed Matter Physics, CEITEC, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - E Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A A Ünal
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - S Valencia
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - M Dunst
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - J Minár
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany.,New Technologies Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - E Golias
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - L V Yashina
- Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia
| | - A Ney
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - V Holý
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 12116 Prague, Czech Republic
| | - O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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8
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Geck J, Zwiebler M, Gray B, Chakhalian J, Freeland J, He F, Koitzsch A, Komissinskiy P, Schierle E, Sutarto S, Treske U, Vafaee M, Weschke E, Sawatzky GA, Alff L, Macke S, Hamann-Borrero JE. Electronic depth profiles with atomic layer resolution from resonant X-ray reflectivity. Acta Crystallogr A Found Adv 2015. [DOI: 10.1107/s2053273315097545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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9
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Hepting M, Minola M, Frano A, Cristiani G, Logvenov G, Schierle E, Wu M, Bluschke M, Weschke E, Habermeier HU, Benckiser E, Le Tacon M, Keimer B. Tunable Charge and Spin Order in PrNiO_{3} Thin Films and Superlattices. Phys Rev Lett 2014; 113:227206. [PMID: 25494088 DOI: 10.1103/physrevlett.113.227206] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Indexed: 06/04/2023]
Abstract
We use polarized Raman scattering to probe lattice vibrations and charge ordering in 12 nm thick, epitaxially strained PrNiO_{3} films, and in superlattices of PrNiO_{3} with the band insulator PrAlO_{3}. A carefully adjusted confocal geometry is used to eliminate the substrate contribution to the Raman spectra. In films and superlattices under tensile strain which undergo a metal-insulator transition upon cooling, the Raman spectra reveal phonon modes characteristic of charge ordering. These anomalous phonons do not appear in compressively strained films, which remain metallic at all temperatures. For superlattices under compressive strain, the Raman spectra show no evidence of anomalous phonons indicative of charge ordering, while complementary resonant x-ray scattering experiments reveal antiferromagnetic order associated with a modest increase in resistivity upon cooling. This confirms theoretical predictions of a spin density wave phase driven by spatial confinement of the conduction electrons.
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Affiliation(s)
- M Hepting
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - M Minola
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - A Frano
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany and Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - G Cristiani
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - G Logvenov
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - M Wu
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - M Bluschke
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany and Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - E Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - H-U Habermeier
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - E Benckiser
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - M Le Tacon
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - B Keimer
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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Comin R, Frano A, Yee MM, Yoshida Y, Eisaki H, Schierle E, Weschke E, Sutarto R, He F, Soumyanarayanan A, He Y, Le Tacon M, Elfimov IS, Hoffman JE, Sawatzky GA, Keimer B, Damascelli A. Charge order driven by Fermi-arc instability in Bi2Sr(2-x)La(x)CuO(6+δ). Science 2013; 343:390-2. [PMID: 24356115 DOI: 10.1126/science.1242996] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The understanding of the origin of superconductivity in cuprates has been hindered by the apparent diversity of intertwining electronic orders in these materials. We combined resonant x-ray scattering (REXS), scanning-tunneling microscopy (STM), and angle-resolved photoemission spectroscopy (ARPES) to observe a charge order that appears consistently in surface and bulk, and in momentum and real space within one cuprate family, Bi2Sr(2-x)La(x)CuO(6+δ). The observed wave vectors rule out simple antinodal nesting in the single-particle limit but match well with a phenomenological model of a many-body instability of the Fermi arcs. Combined with earlier observations of electronic order in other cuprate families, these findings suggest the existence of a generic charge-ordered state in underdoped cuprates and uncover its intimate connection to the pseudogap regime.
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Affiliation(s)
- R Comin
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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11
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Frano A, Schierle E, Haverkort MW, Lu Y, Wu M, Blanco-Canosa S, Nwankwo U, Boris AV, Wochner P, Cristiani G, Habermeier HU, Logvenov G, Hinkov V, Benckiser E, Weschke E, Keimer B. Orbital control of noncollinear magnetic order in nickel oxide heterostructures. Phys Rev Lett 2013; 111:106804. [PMID: 25166693 DOI: 10.1103/physrevlett.111.106804] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 07/10/2013] [Indexed: 06/03/2023]
Abstract
We have used resonant x-ray diffraction to develop a detailed description of antiferromagnetic ordering in epitaxial superlattices based on two-unit-cell thick layers of the strongly correlated metal LaNiO3. We also report reference experiments on thin films of PrNiO3 and NdNiO3. The resulting data indicate a spiral state whose polarization plane can be controlled by adjusting the Ni d-orbital occupation via two independent mechanisms: epitaxial strain and spatial confinement of the valence electrons. The data are discussed in light of recent theoretical predictions.
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Affiliation(s)
- A Frano
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany and Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - M W Haverkort
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Y Lu
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - M Wu
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - S Blanco-Canosa
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - U Nwankwo
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - A V Boris
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - P Wochner
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - G Cristiani
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - H U Habermeier
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - G Logvenov
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - V Hinkov
- Quantum Matter Institute, University of British Columbia, Vancouver, British Colombia V6T 1Z1, Canada
| | - E Benckiser
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - E Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - B Keimer
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
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12
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Blanco-Canosa S, Frano A, Loew T, Lu Y, Porras J, Ghiringhelli G, Minola M, Mazzoli C, Braicovich L, Schierle E, Weschke E, Le Tacon M, Keimer B. Momentum-dependent charge correlations in YBa2Cu3O6+δ superconductors probed by resonant X-ray scattering: evidence for three competing phases. Phys Rev Lett 2013; 110:187001. [PMID: 23683237 DOI: 10.1103/physrevlett.110.187001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Indexed: 06/02/2023]
Abstract
We use resonant x-ray scattering to determine the momentum-dependent charge correlations in YBa(2)Cu(3) O(6.55) samples with highly ordered chain arrays of oxygen acceptors (ortho-II structure). The results reveal nearly critical, biaxial charge density wave (CDW) correlations at in-plane wave vectors (0.315, 0) and (0, 0.325). The corresponding scattering intensity exhibits a strong uniaxial anisotropy. The CDW amplitude and correlation length are enhanced as superconductivity is weakened by an external magnetic field. Analogous experiments are carried out on a YBa(2)Cu(3)O(6.6) crystal with a dilute concentration of spinless (Zn) impurities, which had earlier been shown to nucleate incommensurate magnetic order. Compared to pristine crystals with the same doping level, the CDW amplitude and correlation length are found to be strongly reduced. These results indicate a three-phase competition between spin-modulated, charge-modulated, and superconducting states in underdoped YBa(2)Cu(3)O(6+δ).
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Affiliation(s)
- S Blanco-Canosa
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
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13
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Abstract
Resonant (elastic) soft x-ray scattering (RSXS) offers a unique element, site and valence specific probe to study spatial modulations of charge, spin and orbital degrees of freedom in solids on the nanoscopic length scale. It is not only used to investigate single-crystalline materials. This method also enables one to examine electronic ordering phenomena in thin films and to zoom into electronic properties emerging at buried interfaces in artificial heterostructures. During the last 20 years, this technique, which combines x-ray scattering with x-ray absorption spectroscopy, has developed into a powerful probe to study electronic ordering phenomena in complex materials and furthermore delivers important information on the electronic structure of condensed matter. This review provides an introduction to the technique, covers the progress in experimental equipment, and gives a survey on recent RSXS studies of ordering in correlated electron systems and at interfaces.
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Affiliation(s)
- J Fink
- Leibniz-Institute for Solid State and Materials Research Dresden, PO Box 270116, D-01171 Dresden, Germany.
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14
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Trabant C, Pontius N, Schierle E, Weschke E, Kachel T, Springholz G, Holldack K, Föhlisch A, Schüßler-Langeheine C. Time and momentum resolved resonant magnetic x-ray diffraction on EuTe. EPJ Web of Conferences 2013. [DOI: 10.1051/epjconf/20134103014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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15
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Ghiringhelli G, Le Tacon M, Minola M, Blanco-Canosa S, Mazzoli C, Brookes NB, De Luca GM, Frano A, Hawthorn DG, He F, Loew T, Moretti Sala M, Peets DC, Salluzzo M, Schierle E, Sutarto R, Sawatzky GA, Weschke E, Keimer B, Braicovich L. Long-Range Incommensurate Charge Fluctuations in (Y,Nd)Ba2Cu3O6+x. Science 2012; 337:821-5. [PMID: 22798406 DOI: 10.1126/science.1223532] [Citation(s) in RCA: 260] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- G Ghiringhelli
- CNR-SPIN, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.
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16
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Tanaka A, Chang CF, Buchholz M, Trabant C, Schierle E, Schlappa J, Schmitz D, Ott H, Metcalf P, Tjeng LH, Schüßler-Langeheine C. Symmetry of orbital order in Fe3O4 studied by Fe L(2,3) resonant x-ray diffraction. Phys Rev Lett 2012; 108:227203. [PMID: 23003646 DOI: 10.1103/physrevlett.108.227203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Indexed: 06/01/2023]
Abstract
We studied the symmetry of the Fe 3d wave function in magnetite below the Verwey temperature T(V) with resonant soft-x-ray diffraction. Although the lattice structure of the low-temperature phase of Fe(3)O(4) is well described by the pseudo-orthorhombic Pmca with a slight monoclinic P2/c distortion, we find that the 3d wave function does not reflect the Pmca symmetry, and its distortion toward monoclinic symmetry is by far larger than that of the lattice. The result supports a scenario in which the Verwey transition involves the ordering of t(2g) orbitals with complex-number coefficients.
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Affiliation(s)
- A Tanaka
- Department of Quantum Matters, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
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17
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Princep AJ, Mulders AM, Schierle E, Weschke E, Hester J, Hutchison WD, Tanaka Y, Terada N, Narumi Y, Nakamura T. High-order Ho multipoles in HoB2C2 observed with soft resonant x-ray diffraction. J Phys Condens Matter 2012; 24:075602. [PMID: 22301486 DOI: 10.1088/0953-8984/24/7/075602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Soft resonant x-ray Bragg diffraction (SRXD) at the Ho M4,5 edges has been used to study Ho 4f multipoles in the combined magnetic and orbitally ordered phase of HoB2C2. A full description of the energy dependence for both σ and π incident x-rays at two different azimuthal angles, as well as the ratio I(σ)/I(π) as a function of azimuthal angle for a selection of energies, allows a determination of the higher order multipole moments of rank 1 (dipole) to 6 (hexacontatetrapole). The Ho 4f multipole moments have been estimated, indicating a dominant hexadecapole (rank 4) order with an almost negligible influence from either the dipole or the octupole magnetic terms. The analysis incorporates both the intra-atomic magnetic and quadrupolar interactions between the 3d core and 4f valence shells as well as the interference of contributions to the scattering that behave differently under time reversal. Comparison of SRXD, neutron diffraction and non-resonant x-ray diffraction shows that the magnetic and quadrupolar order parameters are distinct. The (00½) component of the magnetic order exhibits a Brillouin type increase below the orbital ordering temperature T(Q), while the quadrupolar order increases more sharply. We conclude that the quadrupolar interaction is strong, but quadrupolar order only occurs when the magnetic order gives rise to a quasi-doublet ground state, which results in a lock-in of the orbitals at T(Q).
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Affiliation(s)
- A J Princep
- School of PEMS, UNSW, Canberra, ACT, 2600, Australia
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18
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Schlappa J, Chang CF, Hu Z, Schierle E, Ott H, Weschke E, Kaindl G, Huijben M, Rijnders G, Blank DHA, Tjeng LH, Schüssler-Langeheine C. Resonant soft x-ray scattering from stepped surfaces of SrTiO3. J Phys Condens Matter 2012; 24:035501. [PMID: 22179392 DOI: 10.1088/0953-8984/24/3/035501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We studied the resonant diffraction signal from stepped surfaces of SrTiO(3) at the Ti 2p → 3d (L(2,3)) resonance in comparison with x-ray absorption (XAS) and specular reflectivity data. The steps on the surface form an artificial superstructure suitable as a model system for resonant soft x-ray diffraction. A small step density on the surface is sufficient to produce a well defined diffraction peak. We determined the optical parameters of the sample across the resonance and found that the differences between the energy dependence of the x-ray absorption signal, the specular reflectivity and the step-related peak reflect the different quantities probed in these signals. When recorded at low incidence or detection angles, XAS and specular reflectivity spectra are strongly distorted by the changes of the angle of total reflection with energy. The resonant diffraction spectrum is less affected and can be used as a spectroscopic probe even in less favorable geometries.
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Affiliation(s)
- J Schlappa
- II. Physikalisches Institut, Universität zu Köln, Köln, Germany.
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19
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Wadati H, Geck J, Hawthorn DG, Higuchi T, Hosoda M, Bell C, Hikita Y, Hwang HY, Schussler-Langeheine C, Schierle E, Weschke E, Sawatzky GA. Electronic structure of the SrTiO3/LaAlO3interface revealed by resonant soft x-ray scattering. ACTA ACUST UNITED AC 2011. [DOI: 10.1088/1757-899x/24/1/012012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Partzsch S, Wilkins SB, Hill JP, Schierle E, Weschke E, Souptel D, Büchner B, Geck J. Observation of electronic ferroelectric polarization in multiferroic YMn2O5. Phys Rev Lett 2011; 107:057201. [PMID: 21867092 DOI: 10.1103/physrevlett.107.057201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Indexed: 05/31/2023]
Abstract
We report the observation of a magnetic polarization of the O 2p states in YMn(2)O(5) through the use of soft x-ray resonant scattering at the oxygen K edge. Remarkably, we find that the temperature dependence of the integrated intensity of this signal closely follows the macroscopic electric polarization, and hence is proportional to the ferroelectric order parameter. This is in contrast with the temperature dependence observed at the Mn L(3) edge, which reflects the Mn magnetic order parameter. First-principles calculations provide a microscopic understanding of these results and show that a spin-dependent hybridization of O 2p and Mn 3d states results in a purely electronic contribution to the ferroelectric polarization, which can exist in the absence of lattice distortions.
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Affiliation(s)
- S Partzsch
- Leibniz Institute for Solid State and Materials Research IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany
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21
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Leininger P, Ilakovac V, Joly Y, Schierle E, Weschke E, Bunau O, Berger H, Pouget JP, Foury-Leylekian P. Ground state of the quasi-1D compound BaVS3 resolved by resonant magnetic x-ray scattering. Phys Rev Lett 2011; 106:167203. [PMID: 21599408 DOI: 10.1103/physrevlett.106.167203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Indexed: 05/30/2023]
Abstract
Resonant magnetic x-ray scattering near the vanadium L2,3-absorption edges has been used to investigate the low temperature magnetic structure of high quality BaVS3 single crystals. Below T(N)=31 K, the strong resonance revealed a triple-incommensurate magnetic ordering at the wave vector (0.226 0.226 ξ) in hexagonal notation, with ξ=0.033. The azimuthal-angle dependence of the scattering signal and time-dependent density functional theory simulations indicate an antiferromagnetic order within the ab plane with the spins polarized along a in the monoclinic structure.
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Affiliation(s)
- Ph Leininger
- Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
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22
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Konings S, Schüssler-Langeheine C, Ott H, Weschke E, Schierle E, Zabel H, Goedkoop JB. Magnetic domain fluctuations in an antiferromagnetic film observed with coherent resonant soft x-ray scattering. Phys Rev Lett 2011; 106:077402. [PMID: 21405541 DOI: 10.1103/physrevlett.106.077402] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Revised: 03/17/2010] [Indexed: 05/30/2023]
Abstract
We report the direct observation of slow fluctuations of helical antiferromagnetic domains in an ultrathin holmium film using coherent resonant magnetic x-ray scattering. We observe a gradual increase of the fluctuations in the speckle pattern with increasing temperature, while at the same time a static contribution to the speckle pattern remains. This finding indicates that domain-wall fluctuations occur over a large range of time scales. We ascribe this nonergodic behavior to the strong dependence of the fluctuation rate on the local thickness of the film.
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Affiliation(s)
- S Konings
- Van der Waals-Zeeman Institute, University of Amsterdam, The Netherlands
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23
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Schierle E, Soltwisch V, Schmitz D, Feyerherm R, Maljuk A, Yokaichiya F, Argyriou DN, Weschke E. Cycloidal order of 4f moments as a probe of chiral domains in DyMnO₃. Phys Rev Lett 2010; 105:167207. [PMID: 21231008 DOI: 10.1103/physrevlett.105.167207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Indexed: 05/30/2023]
Abstract
Using soft x-ray diffraction at the Dy-M₅ resonance, pronounced circular dichroism in the ferroelectric phase of DyMnO₃ is observed in connection with sizable b and c components of the Dy-4f magnetic moments. This provides strong evidence for cycloidal order of the 4f moments, corroborating that inversion-symmetry breaking in this material is not accomplished by the Mn spins alone. The 4f circular dichroism allows us to image multiferroic domains that are imprinted on the surface of DyMnO₃ using the local charging by the x-ray beam via the photoelectric effect.
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Affiliation(s)
- E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Str. 15, D-12489 Berlin, Germany
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24
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Bohnenbuck B, Zegkinoglou I, Strempfer J, Nelson CS, Wu HH, Schübler-Langeheine C, Reehuis M, Schierle E, Leininger P, Herrmannsdörfer T, Lang JC, Srajer G, Lin CT, Keimer B. Magnetic structure of RuSr2GdCu2O8 determined by resonant x-ray diffraction. Phys Rev Lett 2009; 102:037205. [PMID: 19257388 DOI: 10.1103/physrevlett.102.037205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Indexed: 05/27/2023]
Abstract
X-ray diffraction with photon energies near the Ru L2-absorption edge was used to detect resonant reflections characteristic of a G-type superstructure in RuSr2GdCu2O8 single crystals. A polarization analysis confirms that these reflections are due to magnetic order of Ru moments, and the azimuthal-angle dependence of the scattering amplitude reveals that the moments lie along a low-symmetry axis with substantial components parallel and perpendicular to the RuO2 layers. Complemented by susceptibility data and a symmetry analysis of the magnetic structure, these results reconcile many of the apparently contradictory findings reported in the literature.
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Affiliation(s)
- B Bohnenbuck
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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25
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Schierle E, Weschke E, Gottberg A, Söllinger W, Heiss W, Springholz G, Kaindl G. Antiferromagnetic order with atomic layer resolution in EuTe(111) films. Phys Rev Lett 2008; 101:267202. [PMID: 19113785 DOI: 10.1103/physrevlett.101.267202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Indexed: 05/27/2023]
Abstract
The temperature dependences of the magnetizations of individual atomic layers across an epitaxial antiferromagnetic EuTe film were derived from virtually background-free magnetic Bragg peaks with pronounced Laue oscillations recorded with soft x rays at the Eu-M5 resonance. The magnetizations of the outermost layers decrease significantly differently from those of bulk layers, in agreement with Heisenberg-Monte Carlo calculations. The results demonstrate the applicability of the method to complex ordering phenomena at surfaces and interfaces of thin films.
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Affiliation(s)
- E Schierle
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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Schlappa J, Schüssler-Langeheine C, Chang CF, Ott H, Tanaka A, Hu Z, Haverkort MW, Schierle E, Weschke E, Kaindl G, Tjeng LH. Direct observation of t2g orbital ordering in magnetite. Phys Rev Lett 2008; 100:026406. [PMID: 18232896 DOI: 10.1103/physrevlett.100.026406] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Indexed: 05/12/2023]
Abstract
Using soft-x-ray diffraction at the site-specific resonances in the Fe L2,3 edge, we find clear evidence for orbital and charge ordering in magnetite below the Verwey transition. The spectra show directly that the (001/2) diffraction peak (in cubic notation) is caused by t2g orbital ordering at octahedral Fe2+ sites and the (001) by a spatial modulation of the t2g occupation.
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Affiliation(s)
- J Schlappa
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
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Schüssler-Langeheine C, Schlappa J, Tanaka A, Hu Z, Chang CF, Schierle E, Benomar M, Ott H, Weschke E, Kaindl G, Friedt O, Sawatzky GA, Lin HJ, Chen CT, Braden M, Tjeng LH. Spectroscopy of stripe order in La1.8Sr0.2NiO4 using resonant soft x-ray diffraction. Phys Rev Lett 2005; 95:156402. [PMID: 16241744 DOI: 10.1103/physrevlett.95.156402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Indexed: 05/05/2023]
Abstract
Strong resonant enhancements of the charge-order and spin-order superstructure-diffraction intensities in La1.8Sr0.2NiO4 are observed when x-ray energies in the vicinity of the Ni L2,3 absorption edges are used. The pronounced photon-energy and polarization dependences of these diffraction intensities allow for a critical determination of the local symmetry of the ordered spin and charge carriers. We found that not only the antiferromagnetic order but also the charge-order superstructure resides within the NiO2 layers; the holes are mainly located on in-plane oxygens surrounding a Ni2+ site with the spins coupled antiparallel in close analogy to Zhang-Rice singlets in the cuprates.
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Affiliation(s)
- C Schüssler-Langeheine
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
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Weschke E, Ott H, Schierle E, Schüssler-Langeheine C, Vyalikh DV, Kaindl G, Leiner V, Ay M, Schmitte T, Zabel H, Jensen PJ. Finite-size effect on magnetic ordering temperatures in long-period antiferromagnets: holmium thin films. Phys Rev Lett 2004; 93:157204. [PMID: 15524935 DOI: 10.1103/physrevlett.93.157204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Revised: 04/28/2004] [Indexed: 05/24/2023]
Abstract
The thickness dependence of the helical antiferromagnetic ordering temperature T(N) was studied for thin Ho metal films by resonant magnetic soft x-ray and neutron diffraction. In contrast with the Curie temperature of ferromagnets, T(N) was found to decrease with film thickness d according to [T(N)(infinity)-T(N)(d)]/T(N)(d) proportional variant (d-d(0))(-lambda(')), where lambda(') is a phenomenological exponent and d(0) is of the order of the bulk magnetic period L(b). These observations are reproduced by mean-field calculations that suggest a linear relationship between d(0) and L(b) in long-period antiferromagnets.
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Affiliation(s)
- E Weschke
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
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Mayer R, Schierle E. [Acid etching technic in the mixed dentition]. Dtsch Zahnarztl Z 1980; 35:520-2. [PMID: 6997013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Clinical experience with defect and filling therapy has been good, even with deciduous teeth, a form of therapy which has not been considered promising because of the "prismless enamel of deciduous teeth". Examination with the scanning electron microscope supported our positive findings. If the aforementioned surface layer is removed mechanically prior to treatment with etching agents, the same retentive etching pattern could be obtained as was found on the remaining teeth. The best results were obtained with a 37% solution of phosphoric acid.
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