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Wu H, Guo J, Zhaxi S, Xu H, Mi S, Wang L, Chen S, Xu R, Ji W, Pang F, Cheng Z. Controllable CVD Growth of 2D Cr 5Te 8 Nanosheets with Thickness-Dependent Magnetic Domains. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37205739 DOI: 10.1021/acsami.3c02446] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
As a unique 2D magnetic material with self-intercalated structure, Cr5Te8 exhibits many intriguing magnetic properties. While its ferromagnetism of Cr5Te8 has been previously reported, the research on its magnetic domain remains unexplored. Herein, we have successfully fabricated 2D Cr5Te8 nanosheets with controlled thickness and lateral size by chemical vapor deposition (CVD). Then magnetic property measurement system revealed Cr5Te8 nanosheets exhibiting intense out-of-plane ferromagnetism with a Curie temperature (TC) of 176 K. Significantly, we reported for the first time two magnetic domains: magnetic bubbles and thickness-dependent maze-like magnetic domains in our Cr5Te8 nanosheets by cryogenic magnetic force microscopy (MFM). The domain width of the maze-like magnetic domains increases rapidly with decreasing sample thickness; meanwhile, the domain contrast decreases. This indicates the dominant role of ferromagnetism shifts from dipolar interactions to magnetic anisotropy. Our research not only establishes a pathway for the controllable growth of 2D magnetic materials but also points toward novel avenues for regulating magnetic phases and methodically tuning domain characteristics.
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Affiliation(s)
- Hanxiang Wu
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Jianfeng Guo
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Suonan Zhaxi
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Hua Xu
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Shuo Mi
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Le Wang
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Shanshan Chen
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Rui Xu
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Wei Ji
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Fei Pang
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Zhihai Cheng
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
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2
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Kwon HY, Yoon HG, Lee C, Chen G, Liu K, Schmid AK, Wu YZ, Choi JW, Won C. Magnetic Hamiltonian parameter estimation using deep learning techniques. SCIENCE ADVANCES 2020; 6:6/39/eabb0872. [PMID: 32978161 PMCID: PMC7518863 DOI: 10.1126/sciadv.abb0872] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/10/2020] [Indexed: 05/16/2023]
Abstract
Understanding spin textures in magnetic systems is extremely important to the spintronics and it is vital to extrapolate the magnetic Hamiltonian parameters through the experimentally determined spin. It can provide a better complementary link between theories and experimental results. We demonstrate deep learning can quantify the magnetic Hamiltonian from magnetic domain images. To train the deep neural network, we generated domain configurations with Monte Carlo method. The errors from the estimations was analyzed with statistical methods and confirmed the network was successfully trained to relate the Hamiltonian parameters with magnetic structure characteristics. The network was applied to estimate experimentally observed domain images. The results are consistent with the reported results, which verifies the effectiveness of our methods. On the basis of our study, we anticipate that the deep learning techniques make a bridge to connect the experimental and theoretical approaches not only in magnetism but also throughout any scientific research.
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Affiliation(s)
- H Y Kwon
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea.
| | - H G Yoon
- Department of Physics, Kyung Hee University, Seoul 02447, South Korea
| | - C Lee
- Department of Physics, Kyung Hee University, Seoul 02447, South Korea
| | - G Chen
- Department of Physics, University of California, Davis, Davis, CA 95616, USA
| | - K Liu
- Department of Physics, University of California, Davis, Davis, CA 95616, USA
- Physics Department, Georgetown University, Washington, DC 20057, USA
| | - A K Schmid
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Y Z Wu
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China
| | - J W Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - C Won
- Department of Physics, Kyung Hee University, Seoul 02447, South Korea.
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3
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Tripathi AK, Kumar D, Puri S. Coarsening dynamics in the Swift-Hohenberg equation with an external field. Phys Rev E 2019; 99:022136. [PMID: 30934234 DOI: 10.1103/physreve.99.022136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Indexed: 11/07/2022]
Abstract
We study the Swift-Hohenberg equation (SHE) in the presence of an external field. The application of the field leads to a phase diagram with three phases, i.e., stripe, hexagon, and uniform. We focus on coarsening after a quench from the uniform to stripe or hexagon regions. For stripe patterns, we find that the length scale associated with the order-parameter structure factor has the same growth exponent (≃1/4) as for the SHE with zero field. The growth process is slower in the case of hexagonal patterns, with the effective growth exponent varying between 1/6 and 1/9, depending on the quench parameters. For deep quenches in the hexagonal phase, the growth process stops at late stages when defect boundaries become pinned.
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Affiliation(s)
- Ashwani K Tripathi
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi - 110067, India.,Center for Soft and Living Matter, Institute for Basic Science, Ulsan 44919, Republic of Korea
| | - Deepak Kumar
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi - 110067, India
| | - Sanjay Puri
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi - 110067, India
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4
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Genoni P, Genuzio F, Menteş TO, Santos B, Sala A, Lenardi C, Locatelli A. Magnetic Patterning by Electron Beam-Assisted Carbon Lithography. ACS APPLIED MATERIALS & INTERFACES 2018; 10:27178-27187. [PMID: 30019889 DOI: 10.1021/acsami.8b07485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the proof of principle of a scalable method for writing the magnetic state by electron-stimulated molecular dissociative adsorption on ultrathin Co on Re(0001). Intense microfocused low-energy electron beams are used to promote the formation of surface carbides and graphitic carbon through the fragmentation of carbon monoxide. Upon annealing at the CO desorption temperature, carbon persists in the irradiated areas, whereas the clean surface is recovered elsewhere, giving origin to chemical patterns with nanometer-sharp edges. The accumulation of carbon is found to induce an in-plane to out-of-plane spin reorientation transition in Co, manifested by the appearance of striped magnetic domains. Irradiation at doses in excess of 1000 L of CO followed by ultrahigh vacuum annealing at 380 °C determines the formation of a graphitic overlayer in the irradiated areas, under which Co exhibits out-of-plane magnetic anisotropy. Domains with opposite magnetization are separated here by chiral Neél walls. Our fabrication protocol adds lateral control to spin reorientation transitions, permitting to tune the magnetic anisotropy within arbitrary regions of mesoscopic size. We envisage applications in the nano-engineering of graphene-spaced stacks exhibiting the desired magnetic state and properties.
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Affiliation(s)
- Pietro Genoni
- CIMAINA, Department of Physics , Università degli Studi di Milano , via Celoria 16 , I-20133 Milan , Italy
| | - Francesca Genuzio
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
| | - Benito Santos
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
| | - Alessandro Sala
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
- Department of Physics , Università degli Studi di Trieste , via Valerio 2 , I-34127 Trieste , Italy
| | - Cristina Lenardi
- CIMAINA, Department of Physics , Università degli Studi di Milano , via Celoria 16 , I-20133 Milan , Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
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5
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Riesch C, Radons G, Magerle R. Pathways to equilibrium orientation fluctuations in finite stripe-forming systems. Phys Rev E 2018; 96:052224. [PMID: 29347679 DOI: 10.1103/physreve.96.052224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Indexed: 11/07/2022]
Abstract
Small-angle orientation fluctuations in ordered stripe-forming systems free of topological defects can exhibit aging and anisotropic growth of two length scales. In infinitely extended systems, the stripe orientation field develops a dominant modulation length λ_{∥}^{*}(t) in the direction parallel to the stripes, which increases with time t as λ_{∥}^{*}(t)∼t^{1/4}. Simultaneously, the orientation correlation length ξ_{⊥}(t) in the direction perpendicular to the stripes increases as ξ_{⊥}(t)∼t^{1/2} [Riesch et al., Interface Focus 7, 20160146 (2017)2042-889810.1098/rsfs.2016.0146]. Here we show that finite systems of size L_{⊥}×L_{∥} with periodic boundary conditions reach equilibrium when the dominant modulation length λ_{∥}^{*}(t) reaches the system size L_{∥} in the stripe direction. The equilibration time τ_{eq}^{∥} is solely determined by L_{∥}, with τ_{eq}^{∥}∼L_{∥}^{4}. In systems with L_{⊥}<L_{∥}^{2}/2πλ_{p}, where λ_{p} is the undulation penetration length, the initial aging and coarsening dynamics changes at the crossover time τ_{C}^{⊥}∼L_{⊥}^{2} to an aging and coarsening dynamics described by the one-dimensional Mullins-Herring equation, before reaching equilibrium at τ_{∥}^{eq}. Our work reveals the two pathways to equilibrium in stripe phases with periodic boundary conditions, the finite-size scaling behavior of equilibrium orientation fluctuations, and the characteristic exponents associated with the influence of a finite system size.
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Affiliation(s)
- Christian Riesch
- Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz, Germany
| | - Günter Radons
- Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz, Germany
| | - Robert Magerle
- Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz, Germany
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6
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Riesch C, Radons G, Magerle R. Scaling properties of ageing orientation fluctuations in stripe phases. Interface Focus 2017; 7:20160146. [PMID: 28630676 PMCID: PMC5474038 DOI: 10.1098/rsfs.2016.0146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We investigate the non-equilibrium dynamics of an ordered stripe-forming system free of topological defects. In particular, we study the ageing and the coarsening of orientation fluctuations parallel and perpendicular to the stripes via computer simulations based on a minimal phase-field model (model B with Coulomb interactions). Under the influence of noise, the stripe orientation field develops fluctuations parallel to the stripes, with the dominant modulation length λ*∥ increasing with time t as λ*∥ ∼ t1/4 and the correlation length perpendicular to the stripes ξ⊥θ increasing as ξ⊥θ ∼ t1/2. We explain these anisotropic coarsening dynamics with an analytic theory based on the linear elastic model for stripe displacements first introduced by Landau and Peierls. We thus obtain the scaling forms and the scaling exponents characterizing the correlation functions and the structure factor of the stripe orientation field. Our results reveal how the coarsening of orientation fluctuations prevents a periodically modulated phase free of topological defects from reaching equilibrium.
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Affiliation(s)
- Christian Riesch
- Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
| | - Günter Radons
- Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
| | - Robert Magerle
- Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
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7
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Real-time observation of domain fluctuations in a two-dimensional magnetic model system. Nat Commun 2015; 6:6832. [PMID: 25902073 PMCID: PMC4423231 DOI: 10.1038/ncomms7832] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 03/04/2015] [Indexed: 11/08/2022] Open
Abstract
Domain patterns of perpendicularly magnetized ultra-thin ferromagnetic films are often determined by the competition of the short range but strong exchange interaction favouring ferromagnetic alignment of magnetic moments and the long range but weak antiferromagnetic dipolar interaction. Detailed phase diagrams of the resulting stripe domain patterns have been evaluated in recent years; however, the domain fluctuations in these pattern forming systems have not been studied in great detail so far. Here we show that domain fluctuations can be observed in ultra-thin two-dimensional ferromagnetic Fe/Ni/Cu(001) films with perpendicular magnetization in the stripe domain phase. Non-stroboscopic time-resolved threshold photoemission electron microscopy with high temporal resolution allows analysing the dynamic fingerprint of the topological excitations in the nematic domain phase. Furthermore, proliferation of domain ending defects in the vicinity of the spin reorientation transition is witnessed.
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8
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Dipolar-energy-activated magnetic domain pattern transformation driven by thermal fluctuations. Nat Commun 2013; 4:2054. [PMID: 23784257 DOI: 10.1038/ncomms3054] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 05/24/2013] [Indexed: 11/08/2022] Open
Abstract
Two-dimensional ferromagnetic layers can serve as a playground for the study of basic physical properties of various pattern forming systems by virtue of their tuneable magnetic properties. Here we use threshold photoemission magnetic circular dichroism in combination with photoemission electron microscopy to investigate ultra-thin ferromagnetic Fe/Ni/Cu(001) films in the stripe domain phase near the spin reorientation transition as a function of film thickness, temperature and effective anisotropy. Here we report a metastable domain state with domain width larger than the thermodynamically stable one as a result of a rapid reduction of the anisotropy. The transformation into the equilibrium state takes place via the propagation of a transition front, which originates from defined steps in the film thickness.
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9
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Makhfudz I, Krüger B, Tchernyshyov O. Inertia and chiral edge modes of a Skyrmion magnetic bubble. PHYSICAL REVIEW LETTERS 2012; 109:217201. [PMID: 23215611 DOI: 10.1103/physrevlett.109.217201] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Indexed: 05/10/2023]
Abstract
The dynamics of a vortex in a thin-film ferromagnet resembles the motion of a charged massless particle in a uniform magnetic field. Similar dynamics is expected for other magnetic textures with a nonzero Skyrmion number. However, recent numerical simulations reveal that Skyrmion magnetic bubbles show significant deviations from this model. We show that a Skyrmion bubble possesses inertia and derive its mass from the standard theory of a thin-film ferromagnet. In addition to center-of-mass motion, other low energy modes are waves on the edge of the bubble traveling with different speeds in opposite directions.
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Affiliation(s)
- Imam Makhfudz
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
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10
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Pighin SA, Billoni OV, Cannas SA. Finite-temperature phase diagram of ultrathin magnetic films without external fields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:051119. [PMID: 23214750 DOI: 10.1103/physreve.86.051119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 10/15/2012] [Indexed: 06/01/2023]
Abstract
We analyze the finite-temperature phase diagram of ultrathin magnetic films by introducing a mean-field theory, valid in the low-anisotropy regime, i.e., close to the spin reorientation transition. The theoretical results are compared with Monte Carlo simulations carried out on a microscopic Heisenberg model. Connections between the finite-temperature behavior and the ground-state properties of the system are established. Several properties of the stripe pattern, such as the presence of canted states, the stripe width variation phenomenon, and the associated magnetization profiles, are also analyzed.
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Affiliation(s)
- Santiago A Pighin
- Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, CNEA, CONICET, Avenida E Bustillo 9500, R8402AGP SC de Bariloche, Argentina.
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11
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Fonseca JSM, Rizzi LG, Alves NA. Stripe-tetragonal phase transition in the two-dimensional Ising model with dipole interactions: partition function zeros approach. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:011103. [PMID: 23005364 DOI: 10.1103/physreve.86.011103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 06/06/2012] [Indexed: 06/01/2023]
Abstract
We have performed multicanonical simulations to study the critical behavior of the two-dimensional Ising model with dipole interactions. This study concerns the thermodynamic phase transitions in the range of the interaction δ where the phase characterized by striped configurations of width h = 1 is observed. Controversial results obtained from local update algorithms have been reported for this region, including the claimed existence of a second-order phase transition line that becomes first order above a tricritical point located somewhere between δ = 0.85 and 1. Our analysis relies on the complex partition function zeros obtained with high statistics from multicanonical simulations. Finite size scaling relations for the leading partition function zeros yield critical exponents ν that are clearly consistent with a single second-order phase transition line, thus excluding such a tricritical point in that region of the phase diagram. This conclusion is further supported by analysis of the specific heat and susceptibility of the orientational order parameter.
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Affiliation(s)
- Jacyana S M Fonseca
- Departamento de Física, FFCLRP, Universidade de São Paulo, Avenida Bandeirantes, 3900 Ribeirão Preto 14040-901, SP, Brazil.
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12
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Donzelli O, Vatucello G, Nizzoli F, Palmeri D, Lucari F, D'Orazio F. Magnetic Stripe Domains in Fe/Ni Multilayers. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-475-513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTMagnetic Fe/Ni multilayers, investigated by Magnetic Force Microscopy (MFM), show a stripe domains structure in which the magnetization is oriented in the film plane. This structure is attributed to the equilibrium configuration between competing in-plane anisotropy of the Ni layers and perpendicular anisotropy due to the thin Fe layers.
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13
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Ezawa M. Giant Skyrmions stabilized by dipole-dipole interactions in thin ferromagnetic films. PHYSICAL REVIEW LETTERS 2010; 105:197202. [PMID: 21231193 DOI: 10.1103/physrevlett.105.197202] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Indexed: 05/30/2023]
Abstract
Motivated by a recent magnetization reversal experiment on a TbFeCo thin film, we study a topological excitation in the anisotropic nonlinear sigma model together with the Zeeman and magnetic dipole-dipole interactions. Dipole-dipole interactions turn a ferromagnet into a frustrated spin system, which allows a nontrivial spin texture such as a giant Skyrmion. We derive an analytic formula for the Skyrmion radius. The radius is controllable by the external magnetic field. It is intriguing that a Skyrmion may have already been observed as a magnetic domain. A salient feature is that a single Skyrmion can be created or destroyed experimentally. An analysis is made also on Skyrmions in chiral magnets.
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Affiliation(s)
- Motohiko Ezawa
- Department of Applied Physics, University of Tokyo, Hongo 7-3-1, 113-8656, Japan
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14
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Saratz N, Lichtenberger A, Portmann O, Ramsperger U, Vindigni A, Pescia D. Experimental phase diagram of perpendicularly magnetized ultrathin ferromagnetic films. PHYSICAL REVIEW LETTERS 2010; 104:077203. [PMID: 20366912 DOI: 10.1103/physrevlett.104.077203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Indexed: 05/29/2023]
Abstract
We image the domain patterns in perpendicularly magnetized ultrathin Fe films on Cu(100) as a function of the temperature T and the applied magnetic field H. Between the low-field stripe phase and the high-field uniform phase we find a bubble phase, consisting of reversed circular domains in a homogeneous background. The curvature of the transition lines in the H-T parameter space is in contrast to the general expectations. The pattern transformations show yet undetected scaling properties.
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Affiliation(s)
- N Saratz
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
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15
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Menteş TO, Locatelli A, Aballe L, Bauer E. Stress induced stripe formation in Pd/W(110). PHYSICAL REVIEW LETTERS 2008; 101:085701. [PMID: 18764637 DOI: 10.1103/physrevlett.101.085701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/12/2008] [Indexed: 05/26/2023]
Abstract
A stress-induced stripe phase of submonolayer Pd on W(110) is observed by low-energy electron microscopy. The temperature dependence of the pattern is explained by the change both in the boundary free energy and elastic relaxation energy due to the increasing boundary width. The stripes are shown to disorder when the correlation length of the condensed phase becomes comparable to its period, while the condensate to lattice-gas transition takes place at a higher temperature, as revealed by low-energy electron diffraction.
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Affiliation(s)
- T O Menteş
- Sincrotrone Trieste S.C.p.A., Basovizza-Trieste 34012, Italy
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16
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Iunin YL, Kabanov YP, Nikitenko VI, Cheng XM, Clarke D, Tretiakov OA, Tchernyshyov O, Shapiro AJ, Shull RD, Chien CL. Asymmetric domain nucleation and unusual magnetization reversal in ultrathin Co films with perpendicular anisotropy. PHYSICAL REVIEW LETTERS 2007; 98:117204. [PMID: 17501087 DOI: 10.1103/physrevlett.98.117204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Indexed: 05/15/2023]
Abstract
We report unexpected phenomena during magnetization reversal in ultrathin Co films and Co/Pt multilayers with perpendicular anisotropy. Using magneto-optical Kerr microscopy and magnetic force microscopy we have observed asymmetrical nucleation centers where the reversal begins for one direction of the field only and is characterized by an acute asymmetry of domain-wall mobility. We have also observed magnetic domains with a continuously varying average magnetization, which can be explained in terms of the coexistence of three magnetic phases: up, down, and striped.
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Affiliation(s)
- Y L Iunin
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka 142432, Russia
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17
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Concha A, McIver JW, Mellado P, Clarke D, Tchernyshyov O, Leheny RL. Wrinkling of a bilayer membrane. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:016609. [PMID: 17358277 DOI: 10.1103/physreve.75.016609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Indexed: 05/14/2023]
Abstract
The buckling of elastic bodies is a common phenomenon in the mechanics of solids. Wrinkling of membranes can often be interpreted as buckling under constraints that prohibit large-amplitude deformation. We present a combination of analytic calculations, experiments, and simulations to understand wrinkling patterns generated in a bilayer membrane. The model membrane is composed of a flexible spherical shell that is under tension and that is circumscribed by a stiff, essentially incompressible strip with bending modulus B . When the tension is reduced sufficiently to a value sigma , the strip forms wrinkles with a uniform wavelength found theoretically and experimentally to be lambda=2pi(B/sigma)(1/3). Defects in this pattern appear for rapid changes in tension. Comparison between experiment and simulation further shows that, with larger reduction of tension, a second generation of wrinkles with longer wavelength appears only when B is sufficiently small.
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Affiliation(s)
- A Concha
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
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18
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Leaf G, Kaper H, Yan M, Novosad V, Vavassori P, Camley RE, Grimsditch M. Dynamic origin of stripe domains. PHYSICAL REVIEW LETTERS 2006; 96:017201. [PMID: 16486507 DOI: 10.1103/physrevlett.96.017201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Indexed: 05/06/2023]
Abstract
We investigate stripe domain formation in nanometer sized Co bars. The magnetic equilibrium states and the magnetic spin wave frequencies are obtained from micromagnetic-like simulations. We find that the lowest frequency standing-wave mode has the same spatial structure as the stripe domains at remanence and it goes soft at the field where the stripe domains emerge. We show, therefore, that the final domain structure at remanence, which is not the configuration with lowest energy, is predicted from a high-field analysis of the frequencies of the standing spin waves.
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Affiliation(s)
- G Leaf
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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19
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Wu J, Cao J. Stability Analysis of Three-Dimensional Colloidal Domains: Quadratic Fluctuations. J Phys Chem B 2005; 109:21342-9. [PMID: 16853768 DOI: 10.1021/jp0524431] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three-dimensional domain patterns can self-assemble in a charged colloidal suspension with competing short-range attraction and long-range Yukawa repulsion. Following the investigation of the ground-state domain shapes in our previous paper, we study the stability of isolated spherical, cylindrical, and lamellar domains with respect to shape fluctuations on boundaries. In the framework of the continuum model, we expand the free energy variation to quadratic terms under the constraint of constant volume. For the three shapes (sphere, cylinder, and lamella) discussed, domains with equilibrium sizes are stable with respect to shape fluctuations, and the stability of domains decreases as the spatial symmetry decreases.
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Affiliation(s)
- Jianlan Wu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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van Gastel R, Plass R, Bartelt NC, Kellogg GL. Thermal motion and energetics of self-assembled domain structures: Pb on Cu(111). PHYSICAL REVIEW LETTERS 2003; 91:055503. [PMID: 12906605 DOI: 10.1103/physrevlett.91.055503] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2002] [Indexed: 05/24/2023]
Abstract
Low energy electron microscope measurements of the thermal motion of 50-200 nm diameter Pb islands on Cu(111) are used to establish the nature and determine the strength of interactions that give rise to self-assembly in this two-dimensional, two-phase system. The results show that self-assembled patterns arise from a temperature-independent surface stress difference of approximately 1.2 N/m between the two phases. With increasing Pb coverage, the domain patterns evolve in a manner consistent with models based on dipolar repulsions caused by elastic interactions due to a surface stress difference.
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Affiliation(s)
- R van Gastel
- Sandia National Laboratories, Albuquerque, New Mexico 87185-1415, USA
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Pierce MS, Moore RG, Sorensen LB, Kevan SD, Hellwig O, Fullerton EE, Kortright JB. Quasistatic x-ray speckle metrology of microscopic magnetic return-point memory. PHYSICAL REVIEW LETTERS 2003; 90:175502. [PMID: 12786080 DOI: 10.1103/physrevlett.90.175502] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2002] [Indexed: 05/24/2023]
Abstract
We have used coherent, resonant, x-ray magnetic speckle patterns to measure the statistical evolution of the microscopic magnetic domains in perpendicular magnetic films as a function of the applied magnetic field. Our work constitutes the first direct, ensemble-averaged study of microscopic magnetic return-point memory, and demonstrates the profound impact of interfacial roughness on this phenomenon. At low fields, the microscopic magnetic domains forget their past history with an exponential field dependence.
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Affiliation(s)
- Michael S Pierce
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
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Portmann O, Vaterlaus A, Pescia D. An inverse transition of magnetic domain patterns in ultrathin films. Nature 2003; 422:701-4. [PMID: 12700756 DOI: 10.1038/nature01538] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2002] [Accepted: 02/21/2003] [Indexed: 11/08/2022]
Abstract
Inverse freezing and inverse melting are processes where a more symmetric phase is found at lower temperatures than at higher temperatures. Such inverse transitions are very rare. Here we report the existence of an inverse transition effect in ultrathin Fe films that are magnetized perpendicular to the film plane. The magnetization of these films is not uniform, but instead manifests itself as stripe domains with opposite perpendicular magnetization. Predictions relating to the disordering of this striped ground state in the limit of monolayer film thicknesses are controversial. Mean-field arguments predict a continuous reduction of the stripe width when the temperature is increased; other studies suggest that topological defects, such as dislocations and disclinations, might penetrate the system and induce geometrical phase transitions. We find, from scanning electron microscopy imaging, that when the temperature is increased, the low-temperature stripe domain structure transforms into a more symmetric, labyrinthine structure. However, at even higher temperatures and before the loss of magnetic order, a re-occurrence of the less symmetric stripe phase is found. Despite the widespread theoretical and experimental work on striped systems, this phase sequence and the microscopic instabilities driving it have not been observed before.
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Affiliation(s)
- O Portmann
- Laboratorium für Festkörperphysik, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland.
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Stoycheva AD, Singer SJ. Computer simulations of a two-dimensional system with competing interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:036706. [PMID: 11909306 DOI: 10.1103/physreve.65.036706] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2001] [Indexed: 05/23/2023]
Abstract
The results and methodology of large scale computer simulations of the two-dimensional dipolar Ising model with long-range interactions are reported. Systems as large as 117,649 particles were studied to elucidate the elementary excitations and phase diagram of two-dimensional systems, such as Langmuir monolayers, thin garnet films, and adsorbed films on solid surfaces, which spontaneously form patterns of stripes, bubbles, and intermediately shaped domains. The challenging numerical investigations of large scale systems with long-range interactions at low temperatures were made possible by combining the fast multipole method and a non-Metropolis Monte Carlo sampling technique. Our simulations provide evidence that, at sufficiently high ratios of the repulsive to the attractive coupling constant for the model, twofold stripe order in the systems of interest is lost through a defect-mediated mechanism. Heat capacity data and the excitations observed in our simulations as the system disorders indicate that it is most likely an instance of a Kosterlitz-Thouless phase transition. The results from simulations with and without external field are in excellent agreement with the predictions of an analytic scaling theory [A. D. Stoycheva and S. J. Singer, Phys. Rev. E 64, 016118 (2001)], confirming the phase diagram furnished by the analytic model. The scaling theory suggests that, under certain conditions, defect-mediated stripe melting may be supplanted by Ising like disordering within stripes for small repulsion strength. A qualitative discussion of a model that supports both disordering mechanisms is presented.
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Affiliation(s)
- Antitsa D Stoycheva
- Department of Chemistry, Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, USA
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Erdin S, Lyuksyutov IF, Pokrovsky VL, Vinokur VM. Topological textures in a ferromagnet-superconductor bilayer. PHYSICAL REVIEW LETTERS 2002; 88:017001. [PMID: 11800979 DOI: 10.1103/physrevlett.88.017001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2001] [Indexed: 05/23/2023]
Abstract
The homogeneous state of a ferromagnet-superconductor bilayer (FSB) with the magnetization perpendicular to the layer can be unstable with respect to the formation of vortices in the superconducting layer. The developing topological instability in the FSB leads to formation of domains in which the direction of the magnetization in the magnetic film and the direction of vorticity in the superconducting film alternate together. This is a new, combined topological structure, which does not appear in isolated layers. Equilibrium domains can appear in the FSB even if the single magnetic film is in a monodomain state.
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Affiliation(s)
- Serkan Erdin
- Department of Physics, Texas A&M University, College Station, TX 77843-4242, USA
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Stoycheva AD, Singer SJ. Stripe melting in a two-dimensional system with competing interactions. PHYSICAL REVIEW LETTERS 2000; 84:4657-4660. [PMID: 10990764 DOI: 10.1103/physrevlett.84.4657] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/1999] [Indexed: 05/23/2023]
Abstract
A model with competing short-ranged attractions and long-ranged repulsions that describes self-organized patterns in systems like Langmuir monolayers, magnetic films, and adsorbed monolayers is studied using numerical simulations and analytic theory. Simulations provide strong evidence confirming that the stripe phase order is destroyed in a defect unbinding transition. Large scale computer simulations are in agreement with an analytic scaling theory, which also predicts an eventual crossover from defect-mediated stripe melting to a spin-disordering (or particle-mixing) mechanism with decreasing repulsion strength.
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Affiliation(s)
- AD Stoycheva
- Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210, USA
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Tretiak S, Chernyak V, Mukamel S. Electronic screening in second order optical polarizabilities of elongated Donor/Acceptor polyenes. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00129-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Duden T, Bauer E. Magnetization Wrinkle in Thin Ferromagnetic Films. PHYSICAL REVIEW LETTERS 1996; 77:2308-2311. [PMID: 10061911 DOI: 10.1103/physrevlett.77.2308] [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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Arlett J, Whitehead JP, MacIsaac AB, De'Bell K. Phase diagram for the striped phase in the two-dimensional dipolar Ising model. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:3394-3402. [PMID: 9986239 DOI: 10.1103/physrevb.54.3394] [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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Schulte O, Klose F, Felsch W. Perpendicular magnetic anisotropy and temperature-dependent reorientation transition of the magnetization in CeH2/Fe multilayers. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:6480-6488. [PMID: 9981877 DOI: 10.1103/physrevb.52.6480] [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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30
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Booth I, MacIsaac AB, Whitehead JP, De'Bell K. Domain structures in ultrathin magnetic films. PHYSICAL REVIEW LETTERS 1995; 75:950-953. [PMID: 10060159 DOI: 10.1103/physrevlett.75.950] [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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Ng KO, Vanderbilt D. Stability of periodic domain structures in a two-dimensional dipolar model. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:2177-2183. [PMID: 9981294 DOI: 10.1103/physrevb.52.2177] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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32
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Abanov A, Kalatsky V, Pokrovsky VL, Saslow WM. Phase diagram of ultrathin ferromagnetic films with perpendicular anisotropy. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:1023-1038. [PMID: 9978253 DOI: 10.1103/physrevb.51.1023] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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