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Friesen C, Osterhage H, Friedlein J, Schlenhoff A, Wiesendanger R, Krause S. Magneto-Seebeck tunneling on the atomic scale. Science 2019; 363:1065-1067. [DOI: 10.1126/science.aat7234] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 02/06/2019] [Indexed: 11/02/2022]
Abstract
The tunneling of spin-polarized electrons across a magnetic tunnel junction driven by a temperature gradient is a fundamental process for the thermal control of electron spin transport. We experimentally investigated the atomic-scale details of this magneto-Seebeck tunneling by placing a magnetic probe tip in close proximity to a magnetic sample at cryogenic temperature, with a vacuum as the tunneling barrier. Heating the tip and measuring the thermopower of the junction while scanning across the spin texture of the sample lead to spin-resolved Seebeck coefficients that can be mapped at atomic-scale lateral resolution. We propose a spin detector for spintronics applications that is driven solely by waste heat, using magneto-Seebeck tunneling to convert spin information into a voltage that can be used for further data processing.
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Coffey D, Diez-Ferrer JL, Serrate D, Ciria M, Fuente CDL, Arnaudas JI. Antiferromagnetic Spin Coupling between Rare Earth Adatoms and Iron Islands Probed by Spin-Polarized Tunneling. Sci Rep 2015; 5:13709. [PMID: 26333417 PMCID: PMC4558548 DOI: 10.1038/srep13709] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/03/2015] [Indexed: 11/16/2022] Open
Abstract
High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths.
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Affiliation(s)
- David Coffey
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - José Luis Diez-Ferrer
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
| | - David Serrate
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - Miguel Ciria
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - César de la Fuente
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - José Ignacio Arnaudas
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
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Sonntag A, Hermenau J, Schlenhoff A, Friedlein J, Krause S, Wiesendanger R. Electric-field-induced magnetic anisotropy in a nanomagnet investigated on the atomic scale. PHYSICAL REVIEW LETTERS 2014; 112:017204. [PMID: 24483926 DOI: 10.1103/physrevlett.112.017204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Indexed: 06/03/2023]
Abstract
Magnetoelectric coupling is studied using the electric field between the tip of a spin-polarized scanning tunneling microscope and a nanomagnet. Our experiments show that a negative (positive) electric field stabilizes (destabilizes) in-plane magnetization against thermal agitation, whereas it destabilizes (stabilizes) out-of-plane magnetization. We conclude that the electric field E induces a uniaxial anisotropy that favors in-plane magnetization for E<0 and out-of-plane magnetization for E>0. Our experiments demonstrate magnetic manipulation on the atomic scale without exploiting spin or charge currents.
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Affiliation(s)
- A Sonntag
- Institute of Applied Physics and Interdisciplinary Nanoscience Center Hamburg, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - J Hermenau
- Institute of Applied Physics and Interdisciplinary Nanoscience Center Hamburg, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - A Schlenhoff
- Institute of Applied Physics and Interdisciplinary Nanoscience Center Hamburg, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - J Friedlein
- Institute of Applied Physics and Interdisciplinary Nanoscience Center Hamburg, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - S Krause
- Institute of Applied Physics and Interdisciplinary Nanoscience Center Hamburg, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - R Wiesendanger
- Institute of Applied Physics and Interdisciplinary Nanoscience Center Hamburg, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
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Prokop J, Tang WX, Zhang Y, Tudosa I, Peixoto TRF, Zakeri K, Kirschner J. Magnons in a ferromagnetic monolayer. PHYSICAL REVIEW LETTERS 2009; 102:177206. [PMID: 19518825 DOI: 10.1103/physrevlett.102.177206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Indexed: 05/27/2023]
Abstract
We report the first observation of high wave vector magnon excitations in a ferromagnetic monolayer. Using spin-polarized electron energy loss spectroscopy, we observed the magnon dispersion in one atomic layer (ML) of Fe on W(110) at 120 K. The magnon energies are small in comparison to the bulk and surface Fe(110) excitations. We find an exchange parameter and magnetic anisotropy similar to that from static measurements. Our results are in sharp contrast to theoretical calculations, indicating that the present understanding of magnetism of the ML Fe requires considerable revision.
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Affiliation(s)
- J Prokop
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
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Krause S, Berbil-Bautista L, Herzog G, Bode M, Wiesendanger R. Current-induced magnetization switching with a spin-polarized scanning tunneling microscope. Science 2007; 317:1537-40. [PMID: 17872442 DOI: 10.1126/science.1145336] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Switching the magnetization of a magnetic bit by injection of a spin-polarized current offers the possibility for the development of innovative high-density data storage technologies. We show how individual superparamagnetic iron nanoislands with typical sizes of 100 atoms can be addressed and locally switched using a magnetic scanning probe tip, thus demonstrating current-induced magnetization reversal across a vacuum barrier combined with the ultimate resolution of spin-polarized scanning tunneling microscopy. Our technique allows us to separate and quantify three fundamental contributions involved in magnetization switching (i.e., current-induced spin torque, heating the island by the tunneling current, and Oersted field effects), thereby providing an improved understanding of the switching mechanism.
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Affiliation(s)
- S Krause
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany.
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Pratzer M, Elmers HJ. Structural and magnetic properties of Co-Fe binary alloy monolayers on W(110). PHYSICAL REVIEW LETTERS 2003; 90:077201. [PMID: 12633268 DOI: 10.1103/physrevlett.90.077201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Indexed: 05/24/2023]
Abstract
We present an experimental investigation of CoxFe1-x monolayers grown on flat and stepped W(110) surfaces. Atomically resolved scanning tunneling microscopy and low energy electron diffraction reveal continuous miscibility and pseudomorphic growth of Co and Fe for 0<or=x<0.6. We observe short range ordered CoFe3-p(2x2) and CoFe-c(2x2) structures in the pseudomorphic monolayer. High Co concentrations lead to a phase separation. The Curie temperature and the ferromagnetic Kerr signal at low temperatures decrease monotonically with increasing Co concentration, finally vanishing at x=0.5.
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Affiliation(s)
- M Pratzer
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
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Wachowiak A, Wiebe J, Bode M, Pietzsch O, Morgenstern M, Wiesendanger R. Direct observation of internal spin structure of magnetic vortex cores. Science 2002; 298:577-80. [PMID: 12386329 DOI: 10.1126/science.1075302] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Thin film nanoscale elements with a curling magnetic structure (vortex) are a promising candidate for future nonvolatile data storage devices. Their properties are strongly influenced by the spin structure in the vortex core. We have used spin-polarized scanning tunneling microscopy on nanoscale iron islands to probe for the first time the internal spin structure of magnetic vortex cores. Using tips coated with a layer of antiferromagnetic chromium, we obtained images of the curling in-plane magnetization around and of the out-of-plane magnetization inside the core region. The experimental data are compared with micromagnetic simulations. The results confirm theoretical predictions that the size and the shape of the vortex core as well as its magnetic field dependence are governed by only two material parameters, the exchange stiffness and the saturation magnetization that determines the stray field energy.
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Affiliation(s)
- A Wachowiak
- Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstr. 11, D-20355 Hamburg, Germany
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Nomura K, Ujihira Y, Vértes A. Applications of conversion electron Mössbauer spectrometry (CEMS). J Radioanal Nucl Chem 1996. [DOI: 10.1007/bf02037942] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Elmers HJ, Hauschild J, Höche H, Gradmann U, Bethge H, Heuer D, Köhler U. Submonolayer magnetism of Fe(110) on W(110): Finite width scaling of stripes and percolation between islands. PHYSICAL REVIEW LETTERS 1994; 73:898-901. [PMID: 10057567 DOI: 10.1103/physrevlett.73.898] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Kohlhepp J, Elmers HJ, Cordes S, Gradmann U. Power laws of magnetization in ferromagnetic monolayers and the two-dimensional Ising model. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:12287-12291. [PMID: 10001264 DOI: 10.1103/physrevb.45.12287] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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