1
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Schimming CD, Reichhardt CJO, Reichhardt C. Vortex Lattices in Active Nematics with Periodic Obstacle Arrays. PHYSICAL REVIEW LETTERS 2024; 132:018301. [PMID: 38242662 DOI: 10.1103/physrevlett.132.018301] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/16/2023] [Indexed: 01/21/2024]
Abstract
We numerically model a two-dimensional active nematic confined by a periodic array of fixed obstacles. Even in the passive nematic, the appearance of topological defects is unavoidable due to planar anchoring by the obstacle surfaces. We show that a vortex lattice state emerges as activity is increased, and that this lattice may be tuned from "ferromagnetic" to "antiferromagnetic" by varying the gap size between obstacles. We map the rich variety of states exhibited by the system as a function of distance between obstacles and activity, including a pinned defect state, motile defects, the vortex lattice, and active turbulence. We demonstrate that the flows in the active turbulent phase can be tuned by the presence of obstacles, and explore the effects of a frustrated lattice geometry on the vortex lattice phase.
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Affiliation(s)
- Cody D Schimming
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C J O Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C Reichhardt
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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2
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Puttock R, Andersen IM, Gatel C, Park B, Rosamond MC, Snoeck E, Kazakova O. Defect-induced monopole injection and manipulation in artificial spin ice. Nat Commun 2022; 13:3641. [PMID: 35752624 PMCID: PMC9233697 DOI: 10.1038/s41467-022-31309-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 06/13/2022] [Indexed: 11/17/2022] Open
Abstract
Lithographically defined arrays of nanomagnets are well placed for application in areas such as probabilistic computing or reconfigurable magnonics due to their emergent collective dynamics and writable magnetic order. Among them are artificial spin ice (ASI), which are arrays of binary in-plane macrospins exhibiting geometric frustration at the vertex interfaces. Macrospin flips in the arrays create topologically protected magnetic charges, or emergent monopoles, which are bound to an antimonopole to conserve charge. In the absence of controllable pinning, it is difficult to manipulate individual monopoles in the array without also influencing other monopole excitations or the counter-monopole charge. Here, we tailor the local magnetic order of a classic ASI lattice by introducing a ferromagnetic defect with shape anisotropy into the array. This creates monopole injection sites at nucleation fields below the critical lattice switching field. Once formed, the high energy monopoles are fixed to the defect site and may controllably propagate through the lattice under stimulation. Defect programing of bound monopoles within the array allows fine control of the pathways of inverted macrospins. Such control is a necessary prerequisite for the realization of functional devices, e. g. reconfigurable waveguide in nanomagnonic applications. Artificial spin ice systems offer a promising platform to study the motion of emergent magnetic monopoles, but controlled nucleation of monopoles is challenging. Here the authors demonstrate controlled injection and propagation of emergent monopoles in an artificial spin ice utilizing ferromagnetic defects.
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Affiliation(s)
- Robert Puttock
- Quantum Materials and Sensors, National Physical Laboratory, Teddington, UK.
| | - Ingrid M Andersen
- Centre d'Elaboration de Materiaux et d'Etudes Structurales, Toulouse, France
| | - Christophe Gatel
- Centre d'Elaboration de Materiaux et d'Etudes Structurales, Toulouse, France
| | - Bumsu Park
- Centre d'Elaboration de Materiaux et d'Etudes Structurales, Toulouse, France
| | - Mark C Rosamond
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, UK
| | - Etienne Snoeck
- Centre d'Elaboration de Materiaux et d'Etudes Structurales, Toulouse, France
| | - Olga Kazakova
- Quantum Materials and Sensors, National Physical Laboratory, Teddington, UK
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3
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Zhang X, Duzgun A, Lao Y, Subzwari S, Bingham NS, Sklenar J, Saglam H, Ramberger J, Batley JT, Watts JD, Bromley D, Chopdekar RV, O'Brien L, Leighton C, Nisoli C, Schiffer P. String Phase in an Artificial Spin Ice. Nat Commun 2021; 12:6514. [PMID: 34764259 PMCID: PMC8585881 DOI: 10.1038/s41467-021-26734-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/19/2021] [Indexed: 11/11/2022] Open
Abstract
One-dimensional strings of local excitations are a fascinating feature of the physical behavior of strongly correlated topological quantum matter. Here we study strings of local excitations in a classical system of interacting nanomagnets, the Santa Fe Ice geometry of artificial spin ice. We measured the moment configuration of the nanomagnets, both after annealing near the ferromagnetic Curie point and in a thermally dynamic state. While the Santa Fe Ice lattice structure is complex, we demonstrate that its disordered magnetic state is naturally described within a framework of emergent strings. We show experimentally that the string length follows a simple Boltzmann distribution with an energy scale that is associated with the system's magnetic interactions and is consistent with theoretical predictions. The results demonstrate that string descriptions and associated topological characteristics are not unique to quantum models but can also provide a simplifying description of complex classical systems with non-trivial frustration.
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Affiliation(s)
- Xiaoyu Zhang
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Ayhan Duzgun
- Theoretical Division and Center for Nonlinear Studies, MS B258, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Yuyang Lao
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Shayaan Subzwari
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
| | - Nicholas S Bingham
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
| | - Joseph Sklenar
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, 48201, USA
| | - Hilal Saglam
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
| | - Justin Ramberger
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Joseph T Batley
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Justin D Watts
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Daniel Bromley
- Department of Physics, University of Liverpool, Liverpool, L69 3BX, United Kingdom
| | - Rajesh V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Liam O'Brien
- Department of Physics, University of Liverpool, Liverpool, L69 3BX, United Kingdom
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Cristiano Nisoli
- Theoretical Division and Center for Nonlinear Studies, MS B258, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Peter Schiffer
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA.
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Department of Physics, Yale University, New Haven, CT, 06511, USA.
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4
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Kempinger S, Huang YS, Lammert P, Vogel M, Hoffmann A, Crespi VH, Schiffer P, Samarth N. Field-Tunable Interactions and Frustration in Underlayer-Mediated Artificial Spin Ice. PHYSICAL REVIEW LETTERS 2021; 127:117203. [PMID: 34558933 DOI: 10.1103/physrevlett.127.117203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 07/24/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Artificial spin ice systems have opened experimental windows into a range of model magnetic systems through the control of interactions among nanomagnet moments. This control has previously been enabled by altering the nanomagnet size and the geometry of their placement. Here we demonstrate that the interactions in artificial spin ice can be further controlled by including a soft ferromagnetic underlayer below the moments. Such a substrate also breaks the symmetry in the array when magnetized, introducing a directional component to the correlations. Using spatially resolved magneto-optical Kerr effect microscopy to image the demagnetized ground states, we show that the correlation of the demagnetized states depends on the direction of the underlayer magnetization. Further, the relative interaction strength of nearest and next-nearest neighbors varies significantly with the array geometry. We exploit this feature to induce frustration in an inherently unfrustrated square lattice geometry, demonstrating new possibilities for effective geometries in two-dimensional nanomagnetic systems.
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Affiliation(s)
- Susan Kempinger
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
- Department of Physics, North Central College, Naperville, Illinois 60540, USA
| | - Yu-Sheng Huang
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Paul Lammert
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Michael Vogel
- Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Platt-Straße 40, 34132 Kassel, Germany
| | - Axel Hoffmann
- Materials Research Laboratory and Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Vincent H Crespi
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Peter Schiffer
- Department of Applied Physics and Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
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5
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Rodríguez-Gallo C, Ortiz-Ambriz A, Tierno P. Topological Boundary Constraints in Artificial Colloidal Ice. PHYSICAL REVIEW LETTERS 2021; 126:188001. [PMID: 34018772 DOI: 10.1103/physrevlett.126.188001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/17/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
The effect of boundaries and how these can be used to influence the bulk behavior in geometrically frustrated systems are both long-standing puzzles, often relegated to a secondary role. Here, we use numerical simulations and "proof of concept" experiments to demonstrate that boundaries can be engineered to control the bulk behavior in a colloidal artificial ice. We show that an antiferromagnetic frontier forces the system to rapidly reach the ground state (GS), as opposed to the commonly implemented open or periodic boundary conditions. We also show that strategically placing defects at the corners generates novel bistable states, or topological strings, which result from competing GS regions in the bulk. Our results could be generalized to other frustrated micro- and nanostructures where boundary conditions may be engineered with lithographic techniques.
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Affiliation(s)
- Carolina Rodríguez-Gallo
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028, Barcelona, Spain
- Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028, Barcelona, Spain
| | - Antonio Ortiz-Ambriz
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028, Barcelona, Spain
- Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028, Barcelona, Spain
| | - Pietro Tierno
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028, Barcelona, Spain
- Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028, Barcelona, Spain
- Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028, Barcelona, Spain
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6
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Makarova K, Strongin V, Titovets I, Syrov A, Zinchenko I, Samoylov V, Hofhuis K, Saccone M, Makarov A, Farhan A, Nefedev K. Low-energy states, ground states, and variable frustrations of the finite-size dipolar Cairo lattices. Phys Rev E 2021; 103:042129. [PMID: 34005950 DOI: 10.1103/physreve.103.042129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/16/2021] [Indexed: 11/07/2022]
Abstract
To investigate the influence of geometric frustration on the properties of low-energy configurations of systems of ferromagnetic nanoislands located on the edges of the Cairo lattice, the model of interacting Ising-like magnetic dipoles is used. By the method of complete enumeration, the densities of states of the Cairo pentagonal lattices of a finite number of Ising-like point dipoles are calculated. The calculated ground and low-energy states for systems with a small number of dipoles can be used to solve the problem of searching for the ground states in a system with a relatively large number of dipoles. It is shown that the ground-state energy of the Cairo pentagonal lattices exhibits nonmonotonic behavior on one of the lattice parameters. The lattice parameters can be used to control the degree of geometric frustration. For the studied lattices of a finite number of Ising dipoles on the Cairo lattice in the ground-state configurations, a number of closed pentagons is observed, which are different from the obtained maximum closed pentagons. The magnetic order in the ground-state configurations obeys the ice rule and the quasi-ice rules.
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Affiliation(s)
- Kseniia Makarova
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation.,Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok, Radio 7, 690041, Russian Federation
| | - Vladislav Strongin
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation.,Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok, Radio 7, 690041, Russian Federation
| | - Iuliia Titovets
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation
| | - Aleksandr Syrov
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation
| | - Ivan Zinchenko
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation.,Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok, Radio 7, 690041, Russian Federation
| | - Victor Samoylov
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation.,Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok, Radio 7, 690041, Russian Federation
| | - Kevin Hofhuis
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, CH-8093 Zurich, Switzerland.,Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Michael Saccone
- Physics Department, University of California, 1156 High Street, Santa Cruz, California 95064, USA
| | - Aleksandr Makarov
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation.,Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok, Radio 7, 690041, Russian Federation
| | - Alan Farhan
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.,Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
| | - Konstantin Nefedev
- School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russky Island, 10 Ajax Bay, 690922, Russian Federation.,Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok, Radio 7, 690041, Russian Federation
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7
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Woods JS, Chen XM, Chopdekar RV, Farmer B, Mazzoli C, Koch R, Tremsin AS, Hu W, Scholl A, Kevan S, Wilkins S, Kwok WK, De Long LE, Roy S, Hastings JT. Switchable X-Ray Orbital Angular Momentum from an Artificial Spin Ice. PHYSICAL REVIEW LETTERS 2021; 126:117201. [PMID: 33798337 DOI: 10.1103/physrevlett.126.117201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
Artificial spin ices (ASI) have been widely investigated as magnetic metamaterials with exotic properties governed by their geometries. In parallel, interest in x-ray photon orbital angular momentum (OAM) has been rapidly growing. Here we show that a square ASI with a patterned topological defect, a double edge dislocation, imparts OAM to scattered x rays. Unlike single dislocations, a double dislocation does not introduce magnetic frustration, and the ASI equilibrates to its antiferromagnetic (AFM) ground state. The topological charge of the defect differs with respect to the structural and magnetic order; thus, x-ray diffraction from the ASI produces photons with even and odd OAM quantum numbers at the structural and AFM Bragg conditions, respectively. The magnetic transitions of the ASI allow the AFM OAM beams to be switched on and off by modest variations of temperature and applied magnetic field. These results demonstrate ASIs can serve as metasurfaces for reconfigurable x-ray optics that could enable selective probes of electronic and magnetic properties.
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Affiliation(s)
- Justin S Woods
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Xiaoqian M Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Rajesh V Chopdekar
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Barry Farmer
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Claudio Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Roland Koch
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Anton S Tremsin
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - Wen Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Andreas Scholl
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Steve Kevan
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Stuart Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Wai-Kwong Kwok
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Lance E De Long
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Sujoy Roy
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J Todd Hastings
- Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506, USA
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8
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Lendinez S, Kaffash MT, Jungfleisch MB. Emergent Spin Dynamics Enabled by Lattice Interactions in a Bicomponent Artificial Spin Ice. NANO LETTERS 2021; 21:1921-1927. [PMID: 33600721 DOI: 10.1021/acs.nanolett.0c03729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Artificial spin ice (ASI) networks are arrays of nanoscaled magnets that can serve both as models for frustration in atomic spin ice as well as for exploring new spin-wave-based strategies to transmit, process, and store information. Here, we exploit the intricate interplay of the magnetization dynamics of two dissimilar ferromagnetic metals arranged on complementary lattice sites in a square ASI to modulate the spin-wave properties effectively. We show that the interaction between the two sublattices results in unique spectra attributed to each sublattice, and we observe inter- and intralattice dynamics facilitated by the distinct magnetization properties of the two materials. The dynamic properties are systematically studied by angular-dependent broadband ferromagnetic resonance and confirmed by micromagnetic simulations. We show that combining materials with dissimilar magnetic properties enables the realization of a wide range of two-dimensional structures, potentially opening the door to new concepts in nanomagnonics.
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Affiliation(s)
- Sergi Lendinez
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States
| | - Mojtaba T Kaffash
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States
| | - M Benjamin Jungfleisch
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States
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9
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Bang W, Silvani R, Hoffmann A, Ketterson JB, Montoncello F, Jungfleisch MB. Ferromagnetic resonance in single vertices and 2D lattices macro-dipoles of elongated nanoelements: measurements and simulations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:065803. [PMID: 33091893 DOI: 10.1088/1361-648x/abc402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report broadband ferromagnetic resonance measurements of the in-plane magnetic field response of three- and four-fold symmetric vertices formed by non-contacting permalloy nano-ellipses together with extended lattices constructed from them. Complementing the experimental data with simulations, we are able to show that, as far as the most intense FMR responses are concerned, the spectra of vertices and lattices can largely be interpreted in terms of a superposition of the underlying hysteretic responses of the individual ellipses, as elemental building blocks of the system. This property suggest that it is possible to understand the orientation of the individual magnetic dipole moments in a dipole network in terms of dynamic measurements alone, thereby offering a powerful tool to analyze the alignment statistics in frustrated systems that are exposed to various magnetic histories.
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Affiliation(s)
- Wonbae Bang
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, United States of America
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, United States of America
| | - R Silvani
- Dipartimento di Fisica e Geologia, Università di Perugia, Perugia, I-06123, Italy
- Istituto Nazionale di Ricerca Metrologica, Torino, I-10135, Italy
| | - A Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, United States of America
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - J B Ketterson
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, United States of America
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, United States of America
| | - F Montoncello
- Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Ferrara, I-44121, Italy
| | - M B Jungfleisch
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, United States of America
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10
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Farhan A, Saccone M, Petersen CF, Dhuey S, Hofhuis K, Mansell R, Chopdekar RV, Scholl A, Lippert T, van Dijken S. Geometrical Frustration and Planar Triangular Antiferromagnetism in Quasi-Three-Dimensional Artificial Spin Architecture. PHYSICAL REVIEW LETTERS 2020; 125:267203. [PMID: 33449705 DOI: 10.1103/physrevlett.125.267203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/01/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
We present a realization of highly frustrated planar triangular antiferromagnetism achieved in a quasi-three-dimensional artificial spin system consisting of monodomain Ising-type nanomagnets lithographically arranged onto a deep-etched silicon substrate. We demonstrate how the three-dimensional spin architecture results in the first direct observation of long-range ordered planar triangular antiferromagnetism, in addition to a highly disordered phase with short-range correlations, once competing interactions are perfectly tuned. Our work demonstrates how escaping two-dimensional restrictions can lead to new types of magnetically frustrated metamaterials.
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Affiliation(s)
- Alan Farhan
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
- Laboratory for Multiscale Materials Experiments (LMX), Paul Scherrer Institut, 5232 Villigen, Switzerland
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - Michael Saccone
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
- Physics Department, University of California, 1156 High Street, Santa Cruz, California 95064, USA
| | - Charlotte F Petersen
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria
| | - Scott Dhuey
- Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - Kevin Hofhuis
- Laboratory for Multiscale Materials Experiments (LMX), Paul Scherrer Institut, 5232 Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland
| | - Rhodri Mansell
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
| | - Rajesh V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - Andreas Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - Thomas Lippert
- Laboratory for Multiscale Materials Experiments (LMX), Paul Scherrer Institut, 5232 Villigen, Switzerland
- Department of Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Sebastiaan van Dijken
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
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11
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Puttock R, Manzin A, Neu V, Garcia-Sanchez F, Fernandez Scarioni A, Schumacher HW, Kazakova O. Modal Frustration and Periodicity Breaking in Artificial Spin Ice. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2003141. [PMID: 32985104 DOI: 10.1002/smll.202003141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/31/2020] [Indexed: 06/11/2023]
Abstract
Here, an artificial spin ice lattice is introduced that exhibits unique Ising and non-Ising behavior under specific field switching protocols because of the inclusion of coupled nanomagnets into the unit cell. In the Ising regime, a magnetic switching mechanism that generates a uni- or bimodal distribution of states dependent on the alignment of the field is demonstrated with respect to the lattice unit cell. In addition, a method for generating a plethora of randomly distributed energy states across the lattice, consisting of Ising and Landau states, is investigated through magnetic force microscopy and micromagnetic modeling. It is demonstrated that the dispersed energy distribution across the lattice is a result of the intrinsic design and can be finely tuned through control of the incident angle of a critical field. The present manuscript explores a complex frustrated environment beyond the 16-vertex Ising model for the development of novel logic-based technologies.
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Affiliation(s)
- Robert Puttock
- National Physical Laboratory, Teddington, TW11 0LW, UK
- Department of Physics, Royal Holloway University of London, Egham Hill, Egham, TW20 0EX, UK
| | | | - Volker Neu
- Leibniz Institute for Solid State and Materials Research Dresden, Dresden, 01069, Germany
| | - Felipe Garcia-Sanchez
- Istituto Nazionale di Ricerca Metrologica, Torino, 10135, Italy
- Departamento de Física Aplicada, University of Salamanca, Pza de la Merced s/n, Salamanca, 37008, Spain
| | | | | | - Olga Kazakova
- National Physical Laboratory, Teddington, TW11 0LW, UK
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12
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Saccone M, Hofhuis K, Bracher D, Kleibert A, van Dijken S, Farhan A. Elevated effective dimension in tree-like nanomagnetic Cayley structures. NANOSCALE 2020; 12:189-194. [PMID: 31803884 DOI: 10.1039/c9nr07510k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using state-of-the-art electron-beam lithography, Ising-type nanomagnets may be defined onto nearly any two-dimensional pattern imaginable. The ability to directly observe magnetic configurations achieved in such artificial spin systems makes them a perfect playground for the realization of artificial spin glasses. However, no experimental realization of a finite-temperature artificial spin glass has been achieved so far. Here, we aim to get a significant step closer in achieving that goal by introducing an artificial spin system with random interactions and increased effective dimension: dipolar Cayley tree. Through synchrotron-based photoemission electron microscopy, we show that an improved balance of ferro- and antiferromagnetic ordering can be achieved in this type of system. This combined with an effective dimension as high as d = 2.72 suggests that future systems generated out of these building blocks can host finite temperature spin glass phases, allowing for real-time observation of glassy dynamics.
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Affiliation(s)
- Michael Saccone
- Physics Department, University of California, 1156 High Street, Santa Cruz, CA 95064, USA. and NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
| | - Kevin Hofhuis
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland and Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - David Bracher
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Armin Kleibert
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Sebastiaan van Dijken
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
| | - Alan Farhan
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland. and Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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13
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Lendinez S, Jungfleisch MB. Magnetization dynamics in artificial spin ice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:013001. [PMID: 31600143 DOI: 10.1088/1361-648x/ab3e78] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this topical review, we present key results of studies on magnetization dynamics in artificial spin ice (ASI), which are arrays of magnetically interacting nanostructures. Recent experimental and theoretical progress in this emerging area, which is at the boundary between research on frustrated magnetism and high-frequency studies of artificially created nanomagnets, is reviewed. The exploration of ASI structures has revealed fascinating discoveries in correlated spin systems. Artificially created spin ice lattices offer unique advantages as they allow for a control of the interactions between the elements by their geometric properties and arrangement. Magnonics, on the other hand, is a field that explores spin dynamics in the gigahertz frequency range in magnetic micro- and nanostructures. In this context, magnonic crystals are particularly important as they allow the modification of spin-wave properties and the observation of band gaps in the resonance spectra. Very recently, there has been considerable progress, experimentally and theoretically, in combining aspects of both fields-artificial spin ice and magnonics-enabling new functionalities in magnonic and spintronic applications using ASI, as well as providing a deeper understanding of geometrical frustration in the gigahertz range. Different approaches for the realization of ASI structures and their experimental characterization in the high-frequency range are described and the appropriate theoretical models and simulations are reviewed. Special attention is devoted to linking these findings to the quasi-static behavior of ASI and dynamic investigations in magnonics in an effort to bridge the gap between both areas further and to stimulate new research endeavors.
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Affiliation(s)
- S Lendinez
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, United States of America
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14
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Chen XM, Farmer B, Woods JS, Dhuey S, Hu W, Mazzoli C, Wilkins SB, Chopdekar RV, Scholl A, Robinson IK, De Long LE, Roy S, Hastings JT. Spontaneous Magnetic Superdomain Wall Fluctuations in an Artificial Antiferromagnet. PHYSICAL REVIEW LETTERS 2019; 123:197202. [PMID: 31765174 DOI: 10.1103/physrevlett.123.197202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/16/2019] [Indexed: 06/10/2023]
Abstract
Collective dynamics often play an important role in determining the stability of ground states for both naturally occurring materials and metamaterials. We studied the temperature dependent dynamics of antiferromagnetically ordered superdomains in a square artificial spin lattice using soft x-ray photon correlation spectroscopy. We observed an exponential slowing down of superdomain wall motion below the antiferromagnetic onset temperature, similar to the behavior of typical bulk antiferromagnets. Using a continuous time random walk model we show that these superdomain walls undergo low-temperature ballistic and high-temperature diffusive motions.
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Affiliation(s)
- X M Chen
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506, USA
| | - B Farmer
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - J S Woods
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - S Dhuey
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - W Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - S B Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - R V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - I K Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- London Centre for Nanotechnology, University College, Gower Street, London WC1E 6BT, United Kingdom
| | - L E De Long
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - S Roy
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J T Hastings
- Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506, USA
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15
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Geometric frustration in ordered lattices of plasmonic nanoelements. Sci Rep 2019; 9:3529. [PMID: 30837626 PMCID: PMC6401306 DOI: 10.1038/s41598-019-40117-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 02/11/2019] [Indexed: 11/08/2022] Open
Abstract
Inspired by geometrically frustrated magnetic systems, we present the optical response of three cases of hexagonal lattices of plasmonic nanoelements. All of them were designed using a metal-insulator-metal configuration to enhance absorption of light, with elements in close proximity to exploit near-field coupling, and with triangular symmetry to induce frustration of the dipolar polarization in the gaps between neighboring structures. Both simulations and experimental results demonstrate that these systems behave as perfect absorbers in the visible and/or the near infrared. Besides, the numerical study of the time evolution shows that they exhibit a relatively extended time response over which the system fluctuates between localized and collective modes. It is of particular interest the echoed excitation of surface lattice resonance modes, which are still present at long times because of the geometric frustration inherent to the triangular lattice. It is worth noting that the excitation of collective modes is also enhanced in other types of arrays where dipolar excitations of the nanoelements are hampered by the symmetry of the array. However, we would like to emphasize that the enhancement in triangular arrays can be significantly larger because of the inherent geometric incompatibility of dipolar excitations and three-fold symmetry axes.
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16
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Li Y, Paterson GW, Macauley GM, Nascimento FS, Ferguson C, Morley SA, Rosamond MC, Linfield EH, MacLaren DA, Macêdo R, Marrows CH, McVitie S, Stamps RL. Superferromagnetism and Domain-Wall Topologies in Artificial "Pinwheel" Spin Ice. ACS NANO 2019; 13:2213-2222. [PMID: 30588800 DOI: 10.1021/acsnano.8b08884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
For over ten years, arrays of interacting single-domain nanomagnets, referred to as artificial spin ices, have been engineered with the aim to study frustration in model spin systems. Here, we use Fresnel imaging to study the reversal process in "pinwheel" artificial spin ice, a modified square ASI structure obtained by rotating each island by some angle about its midpoint. Our results demonstrate that a simple 45° rotation changes the magnetic ordering from antiferromagnetic to ferromagnetic, creating a superferromagnet which exhibits mesoscopic domain growth mediated by domain wall nucleation and coherent domain propagation. We observe several domain-wall configurations, most of which are direct analogues to those seen in continuous ferromagnetic films. However, charged walls also appear due to the geometric constraints of the system. Changing the orientation of the external magnetic field allows control of the nature of the spin reversal with the emergence of either one- or two-dimensional avalanches. This property of pinwheel ASI could be employed to tune devices based on magnetotransport phenomena such as Hall circuits.
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Affiliation(s)
- Yue Li
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Gary W Paterson
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Gavin M Macauley
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Fabio S Nascimento
- Departamento de Física , Universidade Federal de Viçosa , Viçosa 36570-900 , Minas Gerais , Brazil
| | - Ciaran Ferguson
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Sophie A Morley
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , United Kingdom
- Department of Physics , University of California , Santa Cruz , California 95064 , United States
| | - Mark C Rosamond
- School of Electronic and Electrical Engineering , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Edmund H Linfield
- School of Electronic and Electrical Engineering , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Donald A MacLaren
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Rair Macêdo
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Christopher H Marrows
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Stephen McVitie
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
| | - Robert L Stamps
- SUPA, School of Physics and Astronomy , University of Glasgow , Glasgow G12 8QQ , United Kingdom
- Department of Physics and Astronomy , University of Manitoba , Manitoba R3T 2N2 , Canada
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17
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Libál A, Lee DY, Ortiz-Ambriz A, Reichhardt C, Reichhardt CJO, Tierno P, Nisoli C. Ice rule fragility via topological charge transfer in artificial colloidal ice. Nat Commun 2018; 9:4146. [PMID: 30297820 PMCID: PMC6175946 DOI: 10.1038/s41467-018-06631-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 09/05/2018] [Indexed: 11/09/2022] Open
Abstract
Artificial particle ices are model systems of constrained, interacting particles. They have been introduced theoretically to study ice-manifolds emergent from frustration, along with domain wall and grain boundary dynamics, doping, pinning-depinning, controlled transport of topological defects, avalanches, and memory effects. Recently such particle-based ices have been experimentally realized with vortices in nano-patterned superconductors or gravitationally trapped colloids. Here we demonstrate that, although these ices are generally considered equivalent to magnetic spin ices, they can access a novel spectrum of phenomenologies that are inaccessible to the latter. With experiments, theory and simulations we demonstrate that in mixed coordination geometries, entropy-driven negative monopoles spontaneously appear at a density determined by the vertex-mixture ratio. Unlike its spin-based analogue, the colloidal system displays a "fragile ice" manifold, where local energetics oppose the ice rule, which is instead enforced through conservation of the global topological charge. The fragile colloidal ice, stabilized by topology, can be spontaneously broken by topological charge transfer.
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Affiliation(s)
- András Libál
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.,Mathematics and Computer Science Department, Babeş-Bolyai University, Cluj, 400084, Romania
| | - Dong Yun Lee
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, 08028, España
| | - Antonio Ortiz-Ambriz
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, 08028, España.,Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Barcelona, 08028, Spain
| | - Charles Reichhardt
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | | | - Pietro Tierno
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, 08028, España.,Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona, 08028, Spain.,Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Barcelona, 08028, Spain
| | - Cristiano Nisoli
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA. .,Institute for Materials Science, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
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18
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Nisoli C. Unexpected Phenomenology in Particle-Based Ice Absent in Magnetic Spin Ice. PHYSICAL REVIEW LETTERS 2018; 120:167205. [PMID: 29756919 DOI: 10.1103/physrevlett.120.167205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Indexed: 06/08/2023]
Abstract
While particle-based ices are often considered essentially equivalent to magnet-based spin ices, the two differ essentially in frustration and energetics. We show that at equilibrium particle-based ices correspond exactly to spin ices coupled to a background field. In trivial geometries, such a field has no effect, and the two systems are indeed thermodynamically equivalent. In other cases, however, the field controls a richer phenomenology, absent in magnetic ices, and still largely unexplored: ice rule fragility, topological charge transfer, radial polarization, decimation induced disorder, and glassiness.
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Affiliation(s)
- Cristiano Nisoli
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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19
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Direct-write of free-form building blocks for artificial magnetic 3D lattices. Sci Rep 2018; 8:6160. [PMID: 29670129 PMCID: PMC5906635 DOI: 10.1038/s41598-018-24431-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/29/2018] [Indexed: 11/30/2022] Open
Abstract
By the fabrication of periodically arranged nanomagnetic systems it is possible to engineer novel physical properties by realizing artificial lattice geometries that are not accessible via natural crystallization or chemical synthesis. This has been accomplished with great success in two dimensions in the fields of artificial spin ice and magnetic logic devices, to name just two. Although first proposals have been made to advance into three dimensions (3D), established nanofabrication pathways based on electron beam lithography have not been adapted to obtain free-form 3D nanostructures. Here we demonstrate the direct-write fabrication of freestanding ferromagnetic 3D nano-architectures. By employing micro-Hall sensing, we have determined the magnetic stray field generated by our free-form structures in an externally applied magnetic field and we have performed micromagnetic and macro-spin simulations to deduce the spatial magnetization profiles in the structures and analyze their switching behavior. Furthermore we show that the magnetic 3D elements can be combined with other 3D elements of different chemical composition and intrinsic material properties.
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20
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Al Mamoori MKI, Keller L, Pieper J, Barth S, Winkler R, Plank H, Müller J, Huth M. Magnetic Characterization of Direct-Write Free-Form Building Blocks for Artificial Magnetic 3D Lattices. MATERIALS (BASEL, SWITZERLAND) 2018; 11:E289. [PMID: 29439553 PMCID: PMC5848986 DOI: 10.3390/ma11020289] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/07/2018] [Accepted: 02/07/2018] [Indexed: 11/16/2022]
Abstract
Three-dimensional (3D) nanomagnetism, where spin configurations extend into the vertical direction of a substrate plane allow for more complex, hierarchical systems and the design of novel magnetic effects. As an important step towards this goal, we have recently demonstrated the direct-write fabrication of freestanding ferromagnetic 3D nano-architectures of ferromagnetic CoFe in shapes of nano-tree and nano-cube structures by means of focused electron beam induced deposition. Here, we present a comprehensive characterization of the magnetic properties of these structures by local stray-field measurements using a high-resolution micro-Hall magnetometer. Measurements in a wide range of temperatures and different angles of the externally applied magnetic field with respect to the surface plane of the sensor are supported by corresponding micromagnetic simulations, which explain the overall switching behavior of in part rather complex magnetization configurations remarkably well. In particular, the simulations yield coercive and switching fields that are in good quantitative correspondence with the measured coercive and switching fields assuming a bulk metal content of 100 at % consisting of bcc Co 3 Fe. We show that thermally-unstable magnetization states can be repetitively prepared and their lifetime controlled at will, a prerequisite to realizing dynamic and thermally-active magnetic configurations if the building blocks are to be used in lattice structures.
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Affiliation(s)
| | - Lukas Keller
- Institute of Physics, Goethe University, 60438 (M) Frankfurt, Germany.
| | - Jonathan Pieper
- Institute of Physics, Goethe University, 60438 (M) Frankfurt, Germany.
| | - Sven Barth
- Institute of Materials Chemistry, Vienna University of Technology, 1060 Vienna, Austria.
| | - Robert Winkler
- Graz Centre for Electron Microscopy, 8010 Graz, Austria.
| | - Harald Plank
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria.
| | - Jens Müller
- Institute of Physics, Goethe University, 60438 (M) Frankfurt, Germany.
| | - Michael Huth
- Institute of Physics, Goethe University, 60438 (M) Frankfurt, Germany.
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