1
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Rogala M, Bihlmayer G, Dabrowski P, Rodenbücher C, Wrana D, Krok F, Klusek Z, Szot K. Self-reduction of the native TiO 2 (110) surface during cooling after thermal annealing - in-operando investigations. Sci Rep 2019; 9:12563. [PMID: 31467321 PMCID: PMC6715630 DOI: 10.1038/s41598-019-48837-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/07/2019] [Indexed: 11/09/2022] Open
Abstract
We investigate the thermal reduction of TiO2 in ultra-high vacuum. Contrary to what is usually assumed, we observe that the maximal surface reduction occurs not during the heating, but during the cooling of the sample back to room temperature. We describe the self-reduction, which occurs as a result of differences in the energies of defect formation in the bulk and surface regions. The findings presented are based on X-ray photoelectron spectroscopy carried out in-operando during the heating and cooling steps. The presented conclusions, concerning the course of redox processes, are especially important when considering oxides for resistive switching and neuromorphic applications and also when describing the mechanisms related to the basics of operation of solid oxide fuel cells.
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Affiliation(s)
- M Rogala
- University of Lodz, Faculty of Physics and Applied Informatics, 90-236, Lodz, Poland.
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-1 & PGI-7), 52425, Jülich, Germany.
| | - G Bihlmayer
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-1 & PGI-7), 52425, Jülich, Germany
- Forschungszentrum Jülich GmbH, JARA - Fundamentals of Future Information Technologies, 52425, Jülich, Germany
- Forschungszentrum Jülich GmbH, Institute of Advanced Simulation (IAS-1), 52425, Jülich, Germany
| | - P Dabrowski
- University of Lodz, Faculty of Physics and Applied Informatics, 90-236, Lodz, Poland
| | - C Rodenbücher
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-3), 52425, Jülich, Germany
| | - D Wrana
- Jagiellonian University, Marian Smoluchowski Institute of Physics, 30-348, Krakow, Poland
| | - F Krok
- Jagiellonian University, Marian Smoluchowski Institute of Physics, 30-348, Krakow, Poland
| | - Z Klusek
- University of Lodz, Faculty of Physics and Applied Informatics, 90-236, Lodz, Poland
| | - K Szot
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-1 & PGI-7), 52425, Jülich, Germany
- Forschungszentrum Jülich GmbH, JARA - Fundamentals of Future Information Technologies, 52425, Jülich, Germany
- University of Silesia, A. Chełkowski Institute of Physics, 40-007, Katowice, Poland
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2
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Rodenbücher C, Bihlmayer G, Speier W, Kubacki J, Wojtyniak M, Rogala M, Wrana D, Krok F, Szot K. Local surface conductivity of transition metal oxides mapped with true atomic resolution. Nanoscale 2018; 10:11498-11505. [PMID: 29888770 DOI: 10.1039/c8nr02562b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The introduction of transition metal oxides for building nanodevices in information technology promises to overcome the scaling limits of conventional semiconductors and to reduce global power consumption significantly. However, oxide surfaces can exhibit heterogeneity on the nanoscale e.g. due to relaxation, rumpling, reconstruction, or chemical variations which demands for direct characterization of electronic transport phenomena down to the atomic level. Here we demonstrate that conductivity mapping is possible with true atomic resolution using the tip of a local conductivity atomic force microscope (LC-AFM) as the mobile nanoelectrode. The application to the prototypical transition metal oxide TiO2 self-doped by oxygen vacancies reveals the existence of highly confined current paths in the first stage of thermal reduction. Assisted by density functional theory (DFT) we propose that the presence of oxygen vacancies in the surface layer of such materials can introduce short range disturbances of the electronic structure with confinement of metallic states on the sub-nanometre scale. After prolonged reduction, the surfaces undergo reconstruction and the conductivity changes from spot-like to homogeneous as a result of surface transformation. The periodic arrangement of the reconstruction is clearly reflected in the conductivity maps as concluded from the simultaneous friction force and LC-AFM measurements. The second prototype metal oxide SrTiO3 also reveals a comparable transformation in surface conductivity from spot-like to homogeneous upon reduction showing the relevance of nanoscale inhomogeneities for the electronic transport properties and the utility of a high-resolution LC-AFM as a convenient tool to detect them.
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Affiliation(s)
- C Rodenbücher
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-1 & PGI-7), 52425 Jülich, Germany.
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3
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Rodenbücher C, Meuffels P, Bihlmayer G, Speier W, Du H, Schwedt A, Breuer U, Jia CL, Mayer J, Waser R, Szot K. Electrically controlled transformation of memristive titanates into mesoporous titanium oxides via incongruent sublimation. Sci Rep 2018; 8:3774. [PMID: 29491379 PMCID: PMC5830621 DOI: 10.1038/s41598-018-22238-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [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: 11/17/2017] [Accepted: 02/20/2018] [Indexed: 11/11/2022] Open
Abstract
Perovskites such as SrTiO3, BaTiO3, and CaTiO3 have become key materials for future energy-efficient memristive data storage and logic applications due to their ability to switch their resistance reversibly upon application of an external voltage. This resistance switching effect is based on the evolution of nanoscale conducting filaments with different stoichiometry and structure than the original oxide. In order to design and optimize memristive devices, a fundamental understanding of the interaction between electrochemical stress, stoichiometry changes and phase transformations is needed. Here, we follow the approach of investigating these effects in a macroscopic model system. We show that by applying a DC voltage under reducing conditions on a perovskite slab it is possible to induce stoichiometry polarization allowing for a controlled decomposition related to incongruent sublimation of the alkaline earth metal starting in the surface region. This way, self-formed mesoporous layers can be generated which are fully depleted by Sr (or Ba, Ca) but consist of titanium oxides including TiO and Ti3O with tens of micrometre thickness. This illustrates that phase transformations can be induced easily by electrochemical driving forces.
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Affiliation(s)
- C Rodenbücher
- Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
| | - P Meuffels
- Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - G Bihlmayer
- Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- Institute of Advanced Simulation, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - W Speier
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - H Du
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- Gemeinschaftslabor für Elektronenmikroskopie, RWTH Aachen, 52056, Aachen, Germany
| | | | - U Breuer
- Central Institute for Engineering, Electronics and Analytics, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - C-L Jia
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - J Mayer
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- Gemeinschaftslabor für Elektronenmikroskopie, RWTH Aachen, 52056, Aachen, Germany
| | - R Waser
- Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- Institut für Werkstoffe der Elektrotechnik 2, RWTH Aachen, 52056, Aachen, Germany
| | - K Szot
- Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- JARA - Fundamentals of Future Information Technologies, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
- A. Chełkowski Institute of Physics, University of Silesia, 40-007, Katowice, Poland
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4
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Moras P, Bihlmayer G, Vescovo E, Sheverdyaeva PM, Papagno M, Ferrari L, Carbone C. Spin-polarized confined states in Ag films on Fe(1 1 0). J Phys Condens Matter 2017; 29:495806. [PMID: 29091051 DOI: 10.1088/1361-648x/aa9760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Spin- and angle-resolved photoemission spectroscopy of thin Ag(1 1 1) films on ferromagnetic Fe(1 1 0) shows a series of spin-polarized peaks. These features derive from Ag sp-bands, which form quantum well states and resonances due to confinement by a spin-dependent interface potential barrier. The spin-up states are broader and located at higher binding energy than the corresponding spin-down states at [Formula: see text], although the differences attenuate near the Fermi level. The spin-down states display multiple gap openings, which interrupt their parabolic-like dispersion. First-principles calculations attribute these findings to the symmetry- and spin-selective hybridization of the Ag states with the exchange-split bands of the substrate.
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Affiliation(s)
- P Moras
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, 34149 Trieste, Italy
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5
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Belabbes A, Bihlmayer G, Bechstedt F, Blügel S, Manchon A. Hund's Rule-Driven Dzyaloshinskii-Moriya Interaction at 3d-5d Interfaces. Phys Rev Lett 2016; 117:247202. [PMID: 28009218 DOI: 10.1103/physrevlett.117.247202] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 06/06/2023]
Abstract
Using relativistic first-principles calculations, we show that the chemical trend of the Dzyaloshinskii-Moriya interaction (DMI) in 3d-5d ultrathin films follows Hund's first rule with a tendency similar to their magnetic moments in either the unsupported 3d monolayers or 3d-5d interfaces. We demonstrate that, besides the spin-orbit coupling (SOC) effect in inversion asymmetric noncollinear magnetic systems, the driving force is the 3d orbital occupations and their spin-flip mixing processes with the spin-orbit active 5d states control directly the sign and magnitude of the DMI. The magnetic chirality changes are discussed in the light of the interplay between SOC, Hund's first rule, and the crystal-field splitting of d orbitals.
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Affiliation(s)
- A Belabbes
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division (PSE), Thuwal 23955-6900, Saudi Arabia
| | - G Bihlmayer
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
| | - F Bechstedt
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - S Blügel
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany
| | - A Manchon
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division (PSE), Thuwal 23955-6900, Saudi Arabia
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6
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Schirone S, Krasovskii EE, Bihlmayer G, Piquerel R, Gambardella P, Mugarza A. Spin-Flip and Element-Sensitive Electron Scattering in the BiAg2 Surface Alloy. Phys Rev Lett 2015; 114:166801. [PMID: 25955067 DOI: 10.1103/physrevlett.114.166801] [Citation(s) in RCA: 4] [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: 08/28/2014] [Indexed: 06/04/2023]
Abstract
Heavy metal surface alloys represent model systems to study the correlation between electron scattering, spin-orbit interaction, and atomic structure. Here, we investigate the electron scattering from the atomic steps of monolayer BiAg_{2} on Ag(111) using quasiparticle interference measurements and density functional theory. We find that intraband transitions between states of opposite spin projection can occur via a spin-flip backward scattering mechanism driven by the spin-orbit interaction. The spin-flip scattering amplitude depends on the chemical composition of the steps, leading to total confinement for pure Bi step edges, and considerable leakage for mixed Bi-Ag step edges. Additionally, the different localization of the occupied and unoccupied surface bands at Ag and Bi sites leads to a spatial shift of the scattering potential barrier at pure Bi step edges.
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Affiliation(s)
- S Schirone
- ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - E E Krasovskii
- Departamento de Física de Materiales, Facultad de Ciencias Químicas, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Apartado 1072, San Sebastián/Donostia, 20080 Basque Country, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, San Sebastián/Donostia, 20018 Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
| | - G Bihlmayer
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - R Piquerel
- ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - P Gambardella
- ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona, Spain
- Instituciò Catalana de Recerca i Estudis Avancats (ICREA), E-08193 Barcelona, Spain
- Department of Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland
| | - A Mugarza
- ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona, Spain
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7
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Fukushima T, Katayama-Yoshida H, Sato K, Bihlmayer G, Mavropoulos P, Bauer DSG, Zeller R, Dederichs PH. Hubbard U calculations for gap states in dilute magnetic semiconductors. J Phys Condens Matter 2014; 26:274202. [PMID: 24935614 DOI: 10.1088/0953-8984/26/27/274202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
On the basis of constrained density functional theory, we present ab initio calculations for the Hubbard U parameter of transition metal impurities in dilute magnetic semiconductors, choosing Mn in GaN as an example. The calculations are performed by two methods: (i) the Korringa-Kohn-Rostoker (KKR) Green function method for a single Mn impurity in GaN and (ii) the full-potential linearized augmented plane-wave (FLAPW) method for a large supercell of GaN with a single Mn impurity in each cell. By changing the occupancy of the majority t2 gap state of Mn, we determine the U parameter either from the total energy differences E(N + 1) and E(N - 1) of the (N ± 1)-electron excited states with respect to the ground state energy E(N), or by using the single-particle energies for n(0) ± 1/2 occupancies around the charge-neutral occupancy n0 (Janak's transition state model). The two methods give nearly identical results. Moreover the values calculated by the supercell method agree quite well with the Green function values. We point out an important difference between the 'global' U parameter calculated using Janak's theorem and the 'local' U of the Hubbard model.
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Affiliation(s)
- T Fukushima
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
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8
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Barfuss A, Dudy L, Scholz MR, Roth H, Höpfner P, Blumenstein C, Landolt G, Dil JH, Plumb NC, Radovic M, Bostwick A, Rotenberg E, Fleszar A, Bihlmayer G, Wortmann D, Li G, Hanke W, Claessen R, Schäfer J. Elemental topological insulator with tunable Fermi level: strained α-Sn on InSb(001). Phys Rev Lett 2013; 111:157205. [PMID: 24160626 DOI: 10.1103/physrevlett.111.157205] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Indexed: 05/20/2023]
Abstract
We report on the epitaxial fabrication and electronic properties of a topological phase in strained α-Sn on InSb. The topological surface state forms in the presence of an unusual band order not based on direct spin-orbit coupling, as shown in density functional and GW slab-layer calculations. Angle-resolved photoemission including spin detection probes experimentally how the topological spin-polarized state emerges from the second bulk valence band. Moreover, we demonstrate the precise control of the Fermi level by dopants.
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Affiliation(s)
- A Barfuss
- Physikalisches Institut und Röntgen Center for Complex Materials Systems, Universität Würzburg, 97074 Würzburg, Germany
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9
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Moras P, Sheverdyaeva PM, Carbone C, Topwal D, Ferrari L, Bihlmayer G, Ouazi S, Rusponi S, Lehnert A, Brune H. Electronic states of moiré modulated Cu films. J Phys Condens Matter 2012; 24:335502. [PMID: 22813539 DOI: 10.1088/0953-8984/24/33/335502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We examined by low-energy electron diffraction and scanning tunneling microscopy the surface of thin Cu films on Pt(111). The Cu/Pt lattice mismatch induces a moiré modulation for films from 3 to about 10 ML thickness. We used angle-resolved photoemission spectroscopy to examine the effects of this structural modulation on the electronic states of the system. A series of hexagonal- and trigonal-like constant energy contours is found in the proximity of the Cu(111) zone boundaries. These electronic patterns are generated by Cu sp-quantum well state replicas, originating from multiple points of the reciprocal lattice associated with the moiré superstructure. Layer-dependent strain relaxation and hybridization with the substrate bands concur to determine the dispersion and energy position of the Cu Shockley surface state.
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Affiliation(s)
- P Moras
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste, Italy.
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10
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Varykhalov A, Marchenko D, Scholz MR, Rienks EDL, Kim TK, Bihlmayer G, Sánchez-Barriga J, Rader O. Ir(111) surface state with giant Rashba splitting persists under graphene in air. Phys Rev Lett 2012; 108:066804. [PMID: 22401103 DOI: 10.1103/physrevlett.108.066804] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Indexed: 05/31/2023]
Abstract
We reveal a giant Rashba effect (α(R)≈1.3 eV Å) on a surface state of Ir(111) by angle-resolved photoemission and by density functional theory. It is demonstrated that the existence of the surface state, its spin polarization, and the size of its Rashba-type spin-orbit splitting remain unaffected when Ir is covered with graphene. The graphene protection is, in turn, sufficient for the spin-split surface state to survive in ambient atmosphere. We discuss this result along with indications for a topological protection of the surface state.
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Affiliation(s)
- A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Berlin, Germany
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11
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Kimura A, Krasovskii EE, Nishimura R, Miyamoto K, Kadono T, Kanomaru K, Chulkov EV, Bihlmayer G, Shimada K, Namatame H, Taniguchi M. Strong rashba-type spin polarization of the photocurrent from bulk continuum States: experiment and theory for Bi(111). Phys Rev Lett 2010; 105:076804. [PMID: 20868068 DOI: 10.1103/physrevlett.105.076804] [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: 02/15/2010] [Indexed: 05/29/2023]
Abstract
Strong spin polarization of the photocurrent from bulk continuum states of Bi(111) is experimentally observed. On the basis of ab initio one-step photoemission theory the effect is shown to originate from the strong polarization of the initial states at the surface and to be the result of the surface sensitivity of photoemission. Final state effects cause deviations of the k{∥} dependence of polarization from strictly antisymmetric relative to Γ.
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Affiliation(s)
- A Kimura
- Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
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12
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Mathias S, Ruffing A, Deicke F, Wiesenmayer M, Sakar I, Bihlmayer G, Chulkov EV, Koroteev YM, Echenique PM, Bauer M, Aeschlimann M. Quantum-well-induced giant spin-orbit splitting. Phys Rev Lett 2010; 104:066802. [PMID: 20366845 DOI: 10.1103/physrevlett.104.066802] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Indexed: 05/29/2023]
Abstract
We report on the observation of a giant spin-orbit splitting of quantum-well states in the unoccupied electronic structure of a Bi monolayer on Cu(111). Up to now, Rashba-type splittings of this size have been reported exclusively for surface states in a partial band gap. With these quantum-well states we have experimentally identified a second class of states that show a huge spin-orbit splitting. First-principles electronic structure calculations show that the origin of the spin-orbit splitting is due to the perpendicular potential at the surface and interface of the ultrathin Bi film. This finding allows for the direct possibility to tailor spin-orbit splitting by means of thin-film nanofabrication.
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Affiliation(s)
- S Mathias
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany.
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13
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Bobisch CA, Bannani A, Koroteev YM, Bihlmayer G, Chulkov EV, Möller R. Conservation of the lateral electron momentum at a metal-semiconductor interface studied by ballistic electron emission microscopy. Phys Rev Lett 2009; 102:136807. [PMID: 19392390 DOI: 10.1103/physrevlett.102.136807] [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: 12/15/2008] [Indexed: 05/27/2023]
Abstract
We report on ballistic electron emission microscopy and spectroscopy studies on epitaxial (3-5 nm thick) Bi(111) films, grown on n-type Si substrates. The effective barrier heights of the Schottky barrier observed are 0.58 eV for the Bi/Si(100)-(2x1) and 0.68 eV for the Bi/Si(111)-(7x7). At the step edges of the epitaxial films a strong increase of the ballistic electron emission microscopy current is observed for Bi/Si(111)-(7x7), while no increase occurs for Bi/Si(100)-(2x1). These observations can be explained by the conservation of the lateral momentum of the electron at the metal-semiconductor interface.
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Affiliation(s)
- C A Bobisch
- Department of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg, Germany.
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14
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Hsieh D, Xia Y, Wray L, Qian D, Pal A, Dil JH, Osterwalder J, Meier F, Bihlmayer G, Kane CL, Hor YS, Cava RJ, Hasan MZ. Observation of Unconventional Quantum Spin Textures in Topological Insulators. Science 2009; 323:919-22. [DOI: 10.1126/science.1167733] [Citation(s) in RCA: 1003] [Impact Index Per Article: 66.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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15
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Zhou PH, Moras P, Ferrari L, Bihlmayer G, Blügel S, Carbone C. One-dimensional 3d electronic bands of monatomic Cu chains. Phys Rev Lett 2008; 101:036807. [PMID: 18764278 DOI: 10.1103/physrevlett.101.036807] [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: 03/24/2008] [Indexed: 05/26/2023]
Abstract
The electronic structure of an array of monatomic Cu chains grown on the Pt(997) surface has been examined by angle-resolved photoemission. The monatomic wires exhibit properties associated with 3d electron confinement in one dimension. Along the wire direction, the 3d bands states display a dispersive character, with periodicity in reciprocal space defined by the wire array geometry. These observations are compared and analyzed with ab initio calculations based on the full-potential linearized augmented plane-wave method.
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Affiliation(s)
- P H Zhou
- International Center for Theoretical Physics, Trieste, Italy
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16
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Ferriani P, von Bergmann K, Vedmedenko EY, Heinze S, Bode M, Heide M, Bihlmayer G, Blügel S, Wiesendanger R. Atomic-scale spin spiral with a unique rotational sense: Mn monolayer on W(001). Phys Rev Lett 2008; 101:027201. [PMID: 18764220 DOI: 10.1103/physrevlett.101.027201] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Indexed: 05/26/2023]
Abstract
Using spin-polarized scanning tunneling microscopy we show that the magnetic order of 1 monolayer Mn on W(001) is a spin spiral propagating along 110 crystallographic directions. The spiral arises on the atomic scale with a period of about 2.2 nm, equivalent to only 10 atomic rows. Ab initio calculations identify the spin spiral as a left-handed cycloid stabilized by the Dzyaloshinskii-Moriya interaction, imposed by spin-orbit coupling, in the presence of softened ferromagnetic exchange coupling. Monte Carlo simulations explain the formation of a nanoscale labyrinth pattern, originating from the coexistence of the two possible rotational domains, that is intrinsic to the system.
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Affiliation(s)
- P Ferriani
- Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany.
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17
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Atodiresei N, Dederichs PH, Mokrousov Y, Bergqvist L, Bihlmayer G, Blügel S. Controlling the magnetization direction in molecules via their oxidation state. Phys Rev Lett 2008; 100:117207. [PMID: 18517823 DOI: 10.1103/physrevlett.100.117207] [Citation(s) in RCA: 13] [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: 11/17/2007] [Indexed: 05/26/2023]
Abstract
By means of ab initio calculations we predict that it is possible to manipulate the magnetization direction in organic magnetic molecules by changing their oxidation state. We demonstrate this novel effect on the Eu2(C8H8)3 molecule, in which the hybridization of the outer pi ring states with the Eu 4f states causes a redistribution of the orbitals around the Fermi level leading to a strong ferromagnetism due to a hole-mediated exchange mechanism. As a key result, we predict an oscillatory behavior of the easy axis of the magnetization as a function of the oxidation state of the molecule-a new effect, which could lead to new technological applications.
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Affiliation(s)
- N Atodiresei
- Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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18
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Mokrousov Y, Atodiresei N, Bihlmayer G, Heinze S, Blügel S. The interplay of structure and spin-orbit strength in the magnetism of metal-benzene sandwiches: from single molecules to infinite wires. Nanotechnology 2007; 18:495402. [PMID: 20442471 DOI: 10.1088/0957-4484/18/49/495402] [Citation(s) in RCA: 18] [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] [Indexed: 05/29/2023]
Abstract
Based on first-principles density functional theory calculations, we explore the electronic and magnetic properties of experimentally producible sandwiches and infinite wires made of repeating benzene molecules and transition-metal atoms of V, Nb, and Ta. We describe the bonding mechanism in the molecules and in particular concentrate on the origin of magnetism in these structures. We find that all the considered systems have sizable magnetic moments and ferromagnetic spin ordering, with the single exception of the V(3)Bz(4) molecule. By including the spin-orbit coupling into our calculations we determine the easy and hard axes of the magnetic moment, the strength of the uniaxial magnetic anisotropy energy (MAE), relevant for the thermal stability of magnetic orientation, and the change of the electronic structure with respect to the direction of the magnetic moment, important for spin-transport properties. While for the V-based compounds the values of the MAE are only of the order of 0.05-0.5 meV per metal atom, increasing the spin-orbit strength by substituting V with heavier Nb and Ta allows one to achieve an increase in anisotropy values by one to two orders of magnitude. The rigid stability of magnetism in these compounds together with the strong ferromagnetic ordering makes them attractive candidates for spin-polarized transport applications. For a Nb-benzene infinite wire the occurrence of ballistic anisotropic magnetoresistance is demonstrated.
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Affiliation(s)
- Y Mokrousov
- Institute for Applied Physics, University of Hamburg, Jungiusstrasse 9a, 20355 Hamburg, Germany.
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19
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Ferriani P, Turek I, Heinze S, Bihlmayer G, Blügel S. Magnetic phase control in monolayer films by substrate tuning. Phys Rev Lett 2007; 99:187203. [PMID: 17995435 DOI: 10.1103/physrevlett.99.187203] [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: 01/09/2007] [Indexed: 05/25/2023]
Abstract
We propose tailoring exchange interactions in magnetic monolayer films by tuning the adjacent nonmagnetic substrate. As an example, we demonstrate a ferromagnetic-antiferromagnetic phase transition for one monolayer Fe on a Ta(x)W(1-x)(001) surface as a function of the Ta concentration. At the critical Ta concentration, the nearest-neighbor exchange interaction is small and the magnetic phase space is dramatically broadened. Complex magnetic order such as spin spirals, multiple-Q, or even disordered local moment states can occur, offering the possibility of storing information in terms of ferromagnetic dots in an otherwise zero-magnetization state matrix.
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Affiliation(s)
- P Ferriani
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany.
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20
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Bode M, Heide M, von Bergmann K, Ferriani P, Heinze S, Bihlmayer G, Kubetzka A, Pietzsch O, Blügel S, Wiesendanger R. Chiral magnetic order at surfaces driven by inversion asymmetry. Nature 2007; 447:190-3. [PMID: 17495922 DOI: 10.1038/nature05802] [Citation(s) in RCA: 258] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Accepted: 03/30/2007] [Indexed: 11/08/2022]
Abstract
Chirality is a fascinating phenomenon that can manifest itself in subtle ways, for example in biochemistry (in the observed single-handedness of biomolecules) and in particle physics (in the charge-parity violation of electroweak interactions). In condensed matter, magnetic materials can also display single-handed, or homochiral, spin structures. This may be caused by the Dzyaloshinskii-Moriya interaction, which arises from spin-orbit scattering of electrons in an inversion-asymmetric crystal field. This effect is typically irrelevant in bulk metals as their crystals are inversion symmetric. However, low-dimensional systems lack structural inversion symmetry, so that homochiral spin structures may occur. Here we report the observation of magnetic order of a specific chirality in a single atomic layer of manganese on a tungsten (110) substrate. Spin-polarized scanning tunnelling microscopy reveals that adjacent spins are not perfectly antiferromagnetic but slightly canted, resulting in a spin spiral structure with a period of about 12 nm. We show by quantitative theory that this chiral order is caused by the Dzyaloshinskii-Moriya interaction and leads to a left-rotating spin cycloid. Our findings confirm the significance of this interaction for magnets in reduced dimensions. Chirality in nanoscale magnets may play a crucial role in spintronic devices, where the spin rather than the charge of an electron is used for data transmission and manipulation. For instance, a spin-polarized current flowing through chiral magnetic structures will exert a spin-torque on the magnetic structure, causing a variety of excitations or manipulations of the magnetization and giving rise to microwave emission, magnetization switching, or magnetic motors.
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Affiliation(s)
- M Bode
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany.
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21
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Loukakos PA, Lisowski M, Bihlmayer G, Blügel S, Wolf M, Bovensiepen U. Dynamics of the self-energy of the Gd(0001) surface state probed by femtosecond photoemission spectroscopy. Phys Rev Lett 2007; 98:097401. [PMID: 17359194 DOI: 10.1103/physrevlett.98.097401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Indexed: 05/14/2023]
Abstract
Transient changes of the complex self-energy of the 5d(z2) surface state on Gd(0001) after intense optical excitation are investigated by femtosecond time-resolved photoemission. We observe an ultrafast (<100 fs) broadening of the linewidth due to e-e scattering followed by a decrease of the binding energy due to thermal expansion of the lattice. In addition, we resolve a periodic breathing of the band structure which originates from a coherent phonon. An amplitude of 1 pm is derived from the binding energy shift upon lattice displacement calculated by density functional theory.
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Affiliation(s)
- P A Loukakos
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin-Dahlem, Germany
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22
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Hirahara T, Nagao T, Matsuda I, Bihlmayer G, Chulkov EV, Koroteev YM, Echenique PM, Saito M, Hasegawa S. Role of spin-orbit coupling and hybridization effects in the electronic structure of ultrathin Bi films. Phys Rev Lett 2006; 97:146803. [PMID: 17155281 DOI: 10.1103/physrevlett.97.146803] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Indexed: 05/12/2023]
Abstract
The electronic structure of Bi(001) ultrathin films (thickness > or =7 bilayers) on Si(111)-7x7 was studied by angle-resolved photoemission spectroscopy and first-principles calculations. In contrast with the semimetallic nature of bulk Bi, both the experiment and theory demonstrate the metallic character of the films with the Fermi surface formed by spin-orbit-split surface states (SSs) showing little thickness dependence. Below the Fermi level, we clearly detected quantum well states (QWSs) at the M point, which were surprisingly found to be non-spin-orbit split; the films are "electronically symmetric" despite the obvious structural nonequivalence of the top and bottom interfaces. We found that the SSs hybridize with the QWSs near M and lose their spin-orbit-split character.
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Affiliation(s)
- T Hirahara
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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23
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Affiliation(s)
- G. Bihlmayer
- a Institute of Physical Chemistry , University of Vienna , Währingerstraße 42, A-1090 , Vienna , Austria
| | - R. Eibler
- a Institute of Physical Chemistry , University of Vienna , Währingerstraße 42, A-1090 , Vienna , Austria
| | - A. Neckel
- a Institute of Physical Chemistry , University of Vienna , Währingerstraße 42, A-1090 , Vienna , Austria
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24
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Lezaić M, Mavropoulos P, Enkovaara J, Bihlmayer G, Blügel S. Thermal collapse of spin polarization in half-metallic ferromagnets. Phys Rev Lett 2006; 97:026404. [PMID: 16907467 DOI: 10.1103/physrevlett.97.026404] [Citation(s) in RCA: 8] [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: 12/13/2005] [Indexed: 05/11/2023]
Abstract
We propose two novel approaches to study the temperature dependence of the magnetization and the spin polarization at the Fermi level in magnetic compounds, and apply them to half-metallic ferromagnets. We reveal a new mechanism, where the hybridization of states forming the half-metallic gap depends on thermal spin fluctuations and the polarization can drop abruptly at temperatures much lower than the Curie point. We verify this for NiMnSb by ab initio calculations. The thermal properties are studied by mapping ab initio results to an extended Heisenberg model which includes longitudinal fluctuations and is solved by a Monte Carlo method.
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Affiliation(s)
- M Lezaić
- Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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25
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von Bergmann K, Heinze S, Bode M, Vedmedenko EY, Bihlmayer G, Blügel S, Wiesendanger R. Observation of a complex nanoscale magnetic structure in a hexagonal Fe monolayer. Phys Rev Lett 2006; 96:167203. [PMID: 16712267 DOI: 10.1103/physrevlett.96.167203] [Citation(s) in RCA: 4] [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: 12/02/2005] [Indexed: 05/09/2023]
Abstract
We have observed a novel magnetic structure in the pseudomorphic Fe monolayer on Ir(111). Using spin-polarized scanning tunneling microscopy we find a nanometer-sized two-dimensional magnetic unit cell. A collinear magnetic structure is proposed consisting of 15 Fe atoms per unit cell with 7 magnetic moments pointing in one and 8 moments in the opposite direction. First-principles calculations verify that such an unusual magnetic state is indeed lower in energy than all solutions of the classical Heisenberg model. We demonstrate that the complex magnetic structure is induced by the strong Fe-Ir hybridization.
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Affiliation(s)
- K von Bergmann
- Institute of Applied Physics, University of Hamburg, Germany.
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26
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Mokrousov Y, Bihlmayer G, Heinze S, Blügel S. Giant magnetocrystalline anisotropies of 4d transition-metal monowires. Phys Rev Lett 2006; 96:147201. [PMID: 16712114 DOI: 10.1103/physrevlett.96.147201] [Citation(s) in RCA: 20] [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: 11/17/2005] [Indexed: 05/09/2023]
Abstract
The magnetocrystalline anisotropy energy (MAE) for ferromagnetic and antiferromagnetic freestanding monowires of 4d transition metals is investigated on the basis of first-principles calculations. Across the 4d series, the easy axis of the magnetization oscillates between two directions: perpendicular and along the wire axis. The largest values of the MAE occur at the end of the series. Giant values of 30-60 meV/atom can be obtained upon stretching Ru or Rh wires. Ru and Pd chains change the magnetization direction upon wire stretching, opening new perspectives in controlling the spin-dependent ballistic conductance in these structures.
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Affiliation(s)
- Y Mokrousov
- Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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27
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Kubetzka A, Ferriani P, Bode M, Heinze S, Bihlmayer G, von Bergmann K, Pietzsch O, Blügel S, Wiesendanger R. Revealing antiferromagnetic order of the Fe monolayer on W(001): spin-polarized scanning tunneling microscopy and first-principles calculations. Phys Rev Lett 2005; 94:087204. [PMID: 15783926 DOI: 10.1103/physrevlett.94.087204] [Citation(s) in RCA: 15] [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: 08/13/2004] [Indexed: 05/24/2023]
Abstract
We prove that the magnetic ground state of a single monolayer Fe on W(001) is c(2x2) antiferromagnetic, i.e., a checkerboard arrangement of antiparallel magnetic moments. Real space images of this magnetic structure have been obtained with spin-polarized scanning tunneling microscopy. An out-of-plane easy magnetization axis is concluded from measurements in an external magnetic field. The magnetic ground state and anisotropy axis are explained based on first-principles calculations.
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Affiliation(s)
- A Kubetzka
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
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28
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Pascual JI, Bihlmayer G, Koroteev YM, Rust HP, Ceballos G, Hansmann M, Horn K, Chulkov EV, Blügel S, Echenique PM, Hofmann P. Role of spin in quasiparticle interference. Phys Rev Lett 2004; 93:196802. [PMID: 15600862 DOI: 10.1103/physrevlett.93.196802] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Indexed: 05/24/2023]
Abstract
Quasiparticle interference patterns measured by scanning tunneling microscopy can be used to study the local electronic structure of metal surfaces and high-temperature superconductors. Here, we show that even in nonmagnetic systems the spin of the quasiparticles can have a profound effect on the interference patterns. On Bi(110), where the surface state bands are not spin degenerate, the patterns are not related to the dispersion of the electronic states in a simple way. In fact, the features which are expected for the spin-independent situation are absent and the observed interference patterns can be interpreted only by taking spin-conserving scattering events into account.
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Affiliation(s)
- J I Pascual
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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29
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Koroteev YM, Bihlmayer G, Gayone JE, Chulkov EV, Blügel S, Echenique PM, Hofmann P. Strong spin-orbit splitting on bi surfaces. Phys Rev Lett 2004; 93:046403. [PMID: 15323779 DOI: 10.1103/physrevlett.93.046403] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2004] [Indexed: 05/24/2023]
Abstract
Using first-principles calculations and angle-resolved photoemission, we show that the spin-orbit interaction leads to a strong splitting of the surface-state bands on low-index surfaces of Bi. The dispersion of the states and the corresponding Fermi surfaces are profoundly modified in the whole surface Brillouin zone. We discuss the implications of these findings with respect to a proposed surface charge density wave on Bi(111) as well as to the surface screening, surface spin-density waves, electron (hole) dynamics in surface states, and to possible applications to the spintronics.
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Affiliation(s)
- Yu M Koroteev
- Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain and Institute of Strength Physics and Materials Science, Russian Academy of Sciences, 634021, Tomsk, Russia
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30
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Bode M, Heinze S, Kubetzka A, Pietzsch O, Nie X, Bihlmayer G, Blügel S, Wiesendanger R. Magnetization-direction-dependent local electronic structure probed by scanning tunneling spectroscopy. Phys Rev Lett 2002; 89:237205. [PMID: 12485038 DOI: 10.1103/physrevlett.89.237205] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2001] [Indexed: 05/24/2023]
Abstract
Scanning tunneling spectroscopy (STS) of thin Fe films on W(110) shows that the electronic structure of domains and domain walls is different. This experimental result is explained on the basis of first-principles calculations. A detailed analysis reveals that the spin-orbit induced mixing between minority d(xy+xz) and minority d(z(2)) spin states depends on the magnetization direction and changes the local density of states in the vacuum detectable by STS. As a consequence nanometer-scale magnetic structure information is obtained even by using nonmagnetic probe tips.
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Affiliation(s)
- M Bode
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany.
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31
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Wortmann D, Heinze S, Kurz P, Bihlmayer G, Blügel S. Resolving complex atomic-scale spin structures by spin-polarized scanning tunneling microscopy. Phys Rev Lett 2001; 86:4132-4135. [PMID: 11328113 DOI: 10.1103/physrevlett.86.4132] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2000] [Indexed: 05/23/2023]
Abstract
The spin-polarized scanning tunneling microscope (SP-STM) operated in the constant current mode is proposed as a powerful tool to investigate complex atomic-scale magnetic structures of otherwise chemically equivalent atoms. The potential of this approach is demonstrated by successfully resolving the magnetic structure of Cr/Ag(111), which is predicted on the basis of ab initio vector spin-density calculations to be a coplanar noncollinear periodic 120 degrees Néel structure. Different operating modes of the SP-STM are discussed on the basis of the model of Tersoff and Hamann.
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Affiliation(s)
- D Wortmann
- Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany
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32
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Kurz P, Bihlmayer G, Hirai K, Blügel S. Three-dimensional spin structure on a two-dimensional lattice: Mn/Cu(111). Phys Rev Lett 2001; 86:1106-1109. [PMID: 11178021 DOI: 10.1103/physrevlett.86.1106] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2000] [Indexed: 05/23/2023]
Abstract
Based on first-principles vector spin-density total-energy calculations of the magnetic and electronic structure of Cr and Mn transition-metal monolayers on the triangular lattice of a (111) oriented Cu surface, we propose for Mn a three-dimensional noncollinear spin structure on a two-dimensional triangular lattice as magnetic ground state. This new spin structure is a multiple spin-density wave of three row-wise antiferromagnetic spin states and comes about due to magnetic interactions beyond the nearest neighbors and due to higher order spin interactions (i.e., four spin). The magnetic ground state of Cr is a coplanar noncollinear periodic 120 degrees Néel structure.
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Affiliation(s)
- P Kurz
- Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany
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33
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Pampuch C, Rader O, Kachel T, Gudat W, Carbone C, Klasges R, Bihlmayer G, Blugel S, Eberhardt W. One-dimensional spin-polarized quantum-wire states in Au on Ni(110). Phys Rev Lett 2000; 85:2561-2564. [PMID: 10978107 DOI: 10.1103/physrevlett.85.2561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/1999] [Revised: 04/27/2000] [Indexed: 05/23/2023]
Abstract
Au chain structures have been prepared on Ni(110). Au6 s,p-derived features in photoemission spectra are identified as quantum-wire states due to their strong dispersion along the chains and absence of dispersion perpendicular to the chains in agreement with our ab initio calculation of the electronic structure. Spin analysis reveals that the states have minority-spin character showing that the confinement of electrons in the chain structure depends on the electron spin.
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Affiliation(s)
- C Pampuch
- BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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34
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Eisebitt S, Rubensson J, Nicodemus M, Böske T, Blügel S, Eberhardt W, Radermacher K, Mantl S, Bihlmayer G. Electronic structure of buried alpha -FeSi2 and beta -FeSi2 layers: Soft-x-ray-emission and -absorption studies compared to band-structure calculations. Phys Rev B Condens Matter 1994; 50:18330-18340. [PMID: 9976268 DOI: 10.1103/physrevb.50.18330] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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35
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