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Wu Q, Altman MS. Spin polarized low energy electron microscopy of quantum well resonances in Fe films on the Cu-covered W(110) surface. Ultramicroscopy 2013; 130:109-14. [PMID: 23628648 DOI: 10.1016/j.ultramic.2013.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 03/13/2013] [Accepted: 03/13/2013] [Indexed: 11/29/2022]
Abstract
Spin polarized low energy electron microscopy has been used to investigate the quantum size effect (QSE) in electron reflectivity from Fe films grown on a pseudomorphic Cu layer on a W(110) surface. Intensity oscillations caused by the QSE as functions of Fe film thickness and incident electron energy identify quantum well resonance conditions in the film. Evaluation of these intensity oscillations using the phase accumulation model provides information on the unoccupied spin polarized band structure in the Fe film above the vacuum level. We also find evidence that the presence of the non-magnetic Cu layer shifts spin polarized quantum well resonances in the Fe layer uniformly downward in energy by 1.1eV compared to Fe/W(110) films without an interface Cu layer, suggesting that the Cu layer gives a small degree of control over the quantum well resonances.
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Affiliation(s)
- Qiang Wu
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China
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2
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Growth Mode and Surface Structure of Cr Ultrathin Film on Fe/Cu(001). E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2008. [DOI: 10.1380/ejssnt.2008.251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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3
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Zeng C, Kent PRC, Varela M, Eisenbach M, Stocks GM, Torija M, Shen J, Weitering HH. Epitaxial stabilization of ferromagnetism in the nanophase of FeGe. PHYSICAL REVIEW LETTERS 2006; 96:127201. [PMID: 16605951 DOI: 10.1103/physrevlett.96.127201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Indexed: 05/08/2023]
Abstract
Epitaxial nanocrystals of FeGe have been stabilized on Ge(111). The nanocrystals assume a quasi-one-dimensional shape as they grow exclusively along the <110> direction of the Ge(111) substrate, culminating in a compressed monoclinic modification of FeGe. Whereas monoclinic FeGe is antiferromagnetic in the bulk, the nanowires are surprisingly strong ferromagnets below approximately 200 K with an average magnetic moment of 0.8 microB per Fe atom. Density functional calculations indicate an unusual stabilization mechanism for the observed ferromagnetism: lattice compression destabilizes the antiferromagnetic Peierls-like ground state observed in the bulk while increased p-d hybridization suppresses the magnetic moments and stabilizes ferromagnetism.
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Affiliation(s)
- Changgan Zeng
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
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4
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Cr adsorption effect of magnetic property of Fe/Cu(001). E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2006. [DOI: 10.1380/ejssnt.2006.345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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5
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Bernhard T, Baron M, Gruyters M, Winter H. Surface structure of ultrathin Fe films on Cu(001) revisited. PHYSICAL REVIEW LETTERS 2005; 95:087601. [PMID: 16196902 DOI: 10.1103/physrevlett.95.087601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Indexed: 05/04/2023]
Abstract
The structure and magnetism of ultrathin Fe films epitaxially grown on a Cu(001) surface are investigated by grazing scattering of fast H and He atoms or ions. By making use of a new variant of ion beam triangulation based on the detection of the number of emitted electrons, we obtain direct information on the structure of the film surface. We observe for room temperature growth a dominant and defined fcc-like structure. Complex surface reconstructions as reported in recent STM and LEED studies are observed only for cooling and H2 dosing.
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Affiliation(s)
- T Bernhard
- Institut für Physik, Humboldt Universität zu Berlin, Newtonstrasse 15, D-12489 Berlin-Adlershof, Germany
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6
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Torija MA, Gai Z, Myoung N, Plummer EW, Shen J. Frozen low-spin interface in ultrathin Fe films on Cu(111). PHYSICAL REVIEW LETTERS 2005; 95:027201. [PMID: 16090711 DOI: 10.1103/physrevlett.95.027201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Indexed: 05/03/2023]
Abstract
In ultrathin film systems, it is a major challenge to understand how a thickness-driven phase transition proceeds along the cross-sectional direction of the films. We use ultrathin Fe films on Cu(111) as a prototype system to demonstrate how to obtain such information using an in situ scanning tunneling microscope and the surface magneto-optical Kerr effect. The magnetization depth profile of a thickness-driven low-spin to high-spin magnetic phase transition is deduced from the experimental data, which leads us to conclude that a low-spin Fe layer at the Fe/Cu interface stays live upon the phase transition. The magnetically live low-spin phase is believed to be induced by a frozen fcc Fe layer that survives a thickness-driven fcc-->bcc structural transition.
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Affiliation(s)
- M A Torija
- Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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7
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Dunn JH, Karis O, Andersson C, Arvanitis D, Carr R, Abrikosov IA, Sanyal B, Bergqvist L, Eriksson O. Vanishing magnetic interactions in ferromagnetic thin films. PHYSICAL REVIEW LETTERS 2005; 94:217202. [PMID: 16090342 DOI: 10.1103/physrevlett.94.217202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Indexed: 05/03/2023]
Abstract
We have used element-specific hysteresis measurements, based on the x-ray magnetic circular dichroism technique, to investigate magnetic trilayer structures composed of Fe and Ni layers. Within a critical regime we have discovered a class of structures in which the exchange interaction, the mechanism responsible for the macroscopic magnetism, can become vanishingly small. The experimental observations are supported by first principles theory and are explained as arising from a cancellation of several competing magnetic interactions. Hence, we have discovered a system with a novel exchange interaction between magnetic layers in direct contact that replaces the conventional exchange interaction in ferromagnets.
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Bisio F, Terreni S, Gonella G, Floreano L, Morgante A, Canepa M, Mattera L. Temperature driven reversible breakdown of pseudomorphism in ultrathin Fe/Cu3Au films. PHYSICAL REVIEW LETTERS 2004; 93:106103. [PMID: 15447423 DOI: 10.1103/physrevlett.93.106103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Indexed: 05/24/2023]
Abstract
We observe that ultrathin Fe/Cu(3)Au(001) films in the 6-13 A thickness range, beyond the thickness of pseudomorphism breakdown at room temperature, exhibit a temperature dependent structural phase transition in the range T(c) approximately 345-380 K. In the high temperature state the Fe film becomes pseudomorphic, while breakdown of pseudomorphism reversibly occurs as the system is cooled below the transition temperature. The difference between substrate and overlayer thermal expansion coefficient is highlighted as the driving force for the observed transition.
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Affiliation(s)
- F Bisio
- Unità INFM and CNR-IMEM, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova, Italy.
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9
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Enders A, Peterka D, Repetto D, Lin N, Dmitriev A, Kern K. Temperature dependence of the surface anisotropy of Fe ultrathin films on Cu(001). PHYSICAL REVIEW LETTERS 2003; 90:217203. [PMID: 12786584 DOI: 10.1103/physrevlett.90.217203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Indexed: 05/24/2023]
Abstract
We report an experimental approach to separate temperature dependent reversible and irreversible contributions to the perpendicular magnetic anisotropy of Fe films grown at low temperatures on Cu(001) substrates. The surface anisotropy K(S)(T) is found to decrease linearly with temperature, causing a thermally induced spin reorientation into the plane. The irreversible shift of the spin reorientation transition and the coercivity of the iron films are directly correlated to the increasing Fe island size during annealing. The increased coercivity is discussed in terms of domain wall energy inhomogeneities provided by the islands.
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Affiliation(s)
- A Enders
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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Spisák D, Hafner J. Shear instability of gamma-Fe in bulk and in ultrathin films. PHYSICAL REVIEW LETTERS 2002; 88:056101. [PMID: 11863751 DOI: 10.1103/physrevlett.88.056101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2001] [Indexed: 05/23/2023]
Abstract
Using ab initio local-spin-density calculations we demonstrate that along the Bain path describing the transformation of face-centered-cubic (fcc) gamma-Fe into body-centered-cubic (bcc) alpha-Fe, tetragonal Fe is unstable against monoclinic shear deformations producing a nearly bcc structure. In the limit of a monolayer adsorbed on a fcc substrate, the epitaxial constraint suppresses the shear instability, but in ultrathin films with three to six monolayers a striped pattern of near-bcc domains develops, confirming recent observations by scanning tunneling microscopy. A strong correlation between the shear instability and the magnetic state is reported.
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Affiliation(s)
- D Spisák
- Institut für Materialphysik and Center for Computational Materials Science, Universität Wien, Sensengasse 8/12, A-1090 Wien, Austria
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Ruban A, Skriver H, Nørskov J. Local equilibrium properties of metallic surface alloys. SURFACE ALLOYS AND ALLOYS SURFACES 2002. [DOI: 10.1016/s1571-0785(02)80088-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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12
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Biedermann A, Tscheliessnig R, Schmid M, Varga P. Crystallographic structure of ultrathin Fe films on Cu(100). PHYSICAL REVIEW LETTERS 2001; 87:086103. [PMID: 11497964 DOI: 10.1103/physrevlett.87.086103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2001] [Indexed: 05/23/2023]
Abstract
We report the observation of bcc-like crystal structures in 2-4 monolayer (ML) Fe films grown on fcc Cu(100) using scanning tunneling microscopy. The local bcc structure provides a straightforward explanation for their frequently reported outstanding magnetic properties, i.e., ferromagnetic ordering in all layers with a Curie temperature above 300 K. The nonpseudomorphic structure, which becomes pseudomorphic above 4 ML film thickness, is unexpected in terms of conventional rules of thin film growth and stresses the importance of finite thickness effects in ferromagnetic ultrathin films.
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Affiliation(s)
- A Biedermann
- Institut für Allgemeine Physik, Vienna University of Technology, A-1040 Vienna, Austria
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Biedermann A, Schmid M, Varga P. Nucleation of bcc iron in ultrathin fcc films. PHYSICAL REVIEW LETTERS 2001; 86:464-467. [PMID: 11177856 DOI: 10.1103/physrevlett.86.464] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2000] [Indexed: 05/23/2023]
Abstract
Needle-shaped bcc nucleation centers in fcc films of Fe on Cu(100) are observed by scanning tunneling microscopy. They form virtually without mass transfer and nearly under conservation of volume, which causes a large strain within the nascent bcc grain. The corresponding strain energy almost equals the gain in structural energy, rendering the bcc nucleation very sensitive to any effect influencing this subtle balance. We suggest that modifying the film by straining, alloying, or surface adsorption may inhibit the bcc nucleation and lead to thick metastable fcc films.
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Affiliation(s)
- A Biedermann
- Institut für Allgemeine Physik, Vienna University of Technology, A-1040 Vienna, Austria
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14
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Vaterlaus A, Stamm C, Maier U, Pini MG, Politi P, Pescia D. Two-step disordering of perpendicularly magnetized ultrathin films. PHYSICAL REVIEW LETTERS 2000; 84:2247-2250. [PMID: 11017255 DOI: 10.1103/physrevlett.84.2247] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/1999] [Indexed: 05/23/2023]
Abstract
We have imaged the stripe domain structure of perpendicularly magnetized fcc ultrathin Fe films grown on Cu(100). The stripe phase has a strong local orientational order and sustains the two kinds of fluctuations predicted by Abanov et al. [Phys. Rev. B 51, 1023 (1995)]: meandering and dislocations. Before reaching the Curie temperature, the stripes transform into a new and so far unobserved domain structure, characterized by domains with predominantly square corners. We argue that this phase is the tetragonal liquid phase proposed by Abanov et al. to separate the stripe phase from the paramagnetic phase. This two-step disordering is reminiscent of a two-dimensional melting process.
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Affiliation(s)
- A Vaterlaus
- Laboratorium für Festkörperphysik, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
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15
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Rare-earth-containing planar magnetic materials formed using Langmuir–Blodgett technique. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 1999. [DOI: 10.1016/s0928-4931(99)00025-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Lorenz R, Hafner J. Magnetic structure and anisotropy of thin Fe films on Cu(001) substrates. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:15937-15949. [PMID: 9985663 DOI: 10.1103/physrevb.54.15937] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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17
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Dunn JH, Arvanitis D, Mårtensson N. Magnetism of thin Fe films on Cu(100). PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R11157-R11160. [PMID: 9985010 DOI: 10.1103/physrevb.54.r11157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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18
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Gubanka B, Donath M, Passek F. Magnetically split sp-derived states in fcc-like Fe/Cu(001). PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R11153-R11156. [PMID: 9985009 DOI: 10.1103/physrevb.54.r11153] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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19
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Újfalussy B, Szunyogh L, Weinberger P. Magnetic anisotropy in Fe/Cu(001) overlayers and interlayers: The high-moment ferromagnetic phase. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:9883-9890. [PMID: 9984723 DOI: 10.1103/physrevb.54.9883] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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20
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Straub M, Vollmer R, Kirschner J. Surface Magnetism of Ultrathin gamma -Fe Films Investigated by Nonlinear Magneto-optical Kerr Effect. PHYSICAL REVIEW LETTERS 1996; 77:743-746. [PMID: 10062891 DOI: 10.1103/physrevlett.77.743] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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21
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Kirilyuk A, Giergiel J, Shen J, Straub M, Kirschner J. Growth of stabilized gamma -Fe films and their magnetic properties. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:1050-1063. [PMID: 9985373 DOI: 10.1103/physrevb.54.1050] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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22
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Fowler DE, Barth JV. Magnetic anisotropy of glide-distorted fcc and of bcc ultrathin Fe/Cu(001) films. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:5563-5569. [PMID: 9984165 DOI: 10.1103/physrevb.53.5563] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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23
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Kirilyuk A, Giergiel J, Shen J, Kirschner J. Unusual surfactant effect and the stability of pseudomorphic gamma -Fe films. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:11672-11680. [PMID: 9980298 DOI: 10.1103/physrevb.52.r11672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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24
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Shen J, Giergiel J, Kirschner J. Growth and morphology of Ni/Cu(100) ultrathin films: An in situ study using scanning tunneling microscopy. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:8454-8460. [PMID: 9979850 DOI: 10.1103/physrevb.52.8454] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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