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Coughlin AL, Xie D, Yao Y, Zhan X, Chen Q, Hewa-Walpitage H, Zhang X, Guo H, Zhou H, Lou J, Wang J, Li YS, Fertig HA, Zhang S. Near Degeneracy of Magnetic Phases in Two-Dimensional Chromium Telluride with Enhanced Perpendicular Magnetic Anisotropy. ACS NANO 2020; 14:15256-15266. [PMID: 33124799 DOI: 10.1021/acsnano.0c05534] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The discovery of atomically thin van der Waals magnets (e.g., CrI3 and Cr2Ge2Te6) has triggered a renaissance in the study of two-dimensional (2D) magnetism. Most of the 2D magnetic compounds discovered so far host only one single magnetic phase unless the system is at a phase boundary. In this work, we report the near degeneracy of magnetic phases in ultrathin chromium telluride (Cr2Te3) layers with strong perpendicular magnetic anisotropy highly desired for stabilizing 2D magnetic order. Single-crystalline Cr2Te3 nanoplates with a trigonal structure (space group P3̅1c) were grown by chemical vapor deposition. The bulk magnetization measurements suggest a ferromagnetic (FM) order with an enhanced perpendicular magnetic anisotropy, as evidenced by a coercive field as large as ∼14 kOe when the field is applied perpendicular to the basal plane of the thin nanoplates. Magneto-optical Kerr effect studies confirm the intrinsic ferromagnetism and characterize the magnetic ordering temperature of individual nanoplates. First-principles density functional theory calculations suggest the near degeneracy of magnetic orderings with a continuously varying canting from the c-axis FM due to their comparable energy scales, explaining the zero-field kink observed in the magnetic hysteresis loops. Our work highlights Cr2Te3 as a promising 2D Ising system to study magnetic phase coexistence and switches for ultracompact information storage and processing.
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Affiliation(s)
- Amanda L Coughlin
- Department of Physics, Indiana University, Bloomington, Indiana 47405, United States
| | - Dongyue Xie
- Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - Yue Yao
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - Xun Zhan
- Electron Microscope Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Qiang Chen
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Heshan Hewa-Walpitage
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - Xiaohang Zhang
- Center for Nanophysics & Advanced Materials, University of Maryland, College Park, Maryland 20742, United States
| | - Hua Guo
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Haidong Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jun Lou
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Jian Wang
- Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - Yan S Li
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - Herbert A Fertig
- Department of Physics, Indiana University, Bloomington, Indiana 47405, United States
- Quantum Science and Engineering Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Shixiong Zhang
- Department of Physics, Indiana University, Bloomington, Indiana 47405, United States
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
- Quantum Science and Engineering Center, Indiana University, Bloomington, Indiana 47405, United States
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Egelhoff WF. X-Ray Photoelectron and Auger Electron Forward-Scattering Studies of the Epitaxial Growth of Fe on Ag(100). ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-229-27] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractA controversy has arisen in the past year over whether or not the growth of Fe on Ag(100) at room temperature occurs by a layer-by-layer mechanism. The present work attempts to address this controversy with an investigation of the issues, primarily by x-ray photoelectron (XPS) and Auger electron forward scattering, but with important supporting data from low-energy electron diffraction (LEED), and reflection high-energy electron diffraction (RHEED) oscillations. The results of this work suggest that the origin of the controversy lies in different substrate preparation techniques which produce different atomic step densities on the Ag(100) surface. The step sites are implicated as being the initiators of major departures from a layer-by-layer growth mode whenever most of the deposited Fe atoms have sufficient mobility to reach these steps. However, even when the Fe atoms cannot reach these steps it appears that atomic place-exchange occurs with ≥25% of the top-layer Ag atoms. Atomic place-exchange mechanisms, which could account for this intermixing, have been observed in recent molecular-dynamics simulations of epitakial growth. Thus it seems probable that under the conditions that appear to produce layer-by-layer growth, the growth begins as layer-by-layer growth of an FeAg alloy, and only becomes layer-by-layer in pure Fe as the segregating Ag atoms gradually get left behind in the growing Fe film.
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Taroni A, Bramwell ST, Holdsworth PCW. Universal window for two-dimensional critical exponents. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:275233. [PMID: 21694394 DOI: 10.1088/0953-8984/20/27/275233] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Two-dimensional condensed matter is realized in increasingly diverse forms that are accessible to experiment and of potential technological value. The properties of these systems are influenced by many length scales and reflect both generic physics and chemical detail. To unify their physical description is therefore a complex and important challenge. Here we investigate the distribution of experimentally estimated critical exponents, β, that characterize the evolution of the order parameter through the ordering transition. The distribution is found to be bimodal and bounded within a window ∼0.1≤β≤0.25, facts that are only in partial agreement with the established theory of critical phenomena. In particular, the bounded nature of the distribution is impossible to reconcile with the existing theory for one of the major universality classes of two-dimensional behaviour-the XY model with four-fold crystal field-which predicts a spectrum of non-universal exponents bounded only from below. Through a combination of numerical and renormalization group arguments we resolve the contradiction between theory and experiment and demonstrate how the 'universal window' for critical exponents observed in experiment arises from a competition between marginal operators.
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Affiliation(s)
- A Taroni
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
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Arenholz E, Navas E, Starke K, Baumgarten L, Kaindl G. Magnetic circular dichroism in core-level photoemission from Gd, Tb, and Dy in ferromagnetic materials. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:8211-8220. [PMID: 9977431 DOI: 10.1103/physrevb.51.8211] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ortega JE, Himpsel FJ. Inverse photoemission from V, Cr, Mn, Fe, and Co monolayers on Ag(100). PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:16441-16446. [PMID: 10006076 DOI: 10.1103/physrevb.47.16441] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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10
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Hübner W, Falicov LM. Theory of spin-polarized electron-capture spectroscopy in ferromagnetic nickel. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:8783-8793. [PMID: 10004923 DOI: 10.1103/physrevb.47.8783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Strandburg KJ, Hall DW, Liu C, Bader SD. Monte Carlo simulations of the Curie temperature of ultrathin ferromagnetic films. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:10818-10821. [PMID: 10002941 DOI: 10.1103/physrevb.46.10818] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Macciò M, Pini MG, Politi P, Rettori A. Spin-wave magnetization of Fe(110)/Ag(111) superlattices: Quasi-two-dimensional versus three-dimensional temperature dependence and anisotropy effects. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:8276-8281. [PMID: 10002588 DOI: 10.1103/physrevb.46.8276] [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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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: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Weber W, Kerkmann D, Pescia D, Wesner DA, Güntherodt G. Enhancement of the Curie temperature of epitaxial Fe films on W(110) caused by adsorption of submonolayers of Fe, Pd, Ag, and O. PHYSICAL REVIEW LETTERS 1990; 65:2058-2061. [PMID: 10042436 DOI: 10.1103/physrevlett.65.2058] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Rau C, Waters K, Chen N. Angle- and energy-resolved, spin-polarized electron emission spectroscopy to study surface magnetic and electronic properties. PHYSICAL REVIEW LETTERS 1990; 64:1441-1444. [PMID: 10041396 DOI: 10.1103/physrevlett.64.1441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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