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Lee J, Park JW, Cho GY, Yeom HW. Mobile Kink Solitons in a Van der Waals Charge-Density-Wave Layer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2300160. [PMID: 37058741 DOI: 10.1002/adma.202300160] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/18/2023] [Indexed: 06/04/2023]
Abstract
Kinks, point-like geometrical defects along dislocations, domain walls, and DNA, are stable and mobile, as solutions of a sine-Gordon wave equation. While they are widely investigated for crystal deformations and domain wall motions, electronic properties of individual kinks have received little attention. In this work, electronically and topologically distinct kinks are discovered along electronic domain walls in a correlated van der Waals insulator of 1T-TaS2 . Mobile kinks and antikinks are identified as trapped by pinning defects and imaged in scanning tunneling microscopy. Their atomic structures and in-gap electronic states are unveiled, which are mapped approximately into Su-Schrieffer-Heeger solitons. The twelvefold degeneracy of the domain walls in the present system guarantees an extraordinarily large number of distinct kinks and antikinks to emerge. Such large degeneracy together with the robust geometrical nature may be useful for handling multilevel information in van der Waals materials architectures.
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Affiliation(s)
- Jinwon Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 37673, Pohang, Republic of Korea
- Department of Physics, Pohang University of Science and Technology, 37673, Pohang, Republic of Korea
- Leiden Institute of Physics, Leiden University, 2333 CA, Leiden, The Netherlands
| | - Jae Whan Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 37673, Pohang, Republic of Korea
| | - Gil Young Cho
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 37673, Pohang, Republic of Korea
- Department of Physics, Pohang University of Science and Technology, 37673, Pohang, Republic of Korea
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 37673, Pohang, Republic of Korea
- Department of Physics, Pohang University of Science and Technology, 37673, Pohang, Republic of Korea
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2
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Bagri A, Jana A, Panchal G, Chowdhury S, Raj R, Kumar M, Gupta M, Reddy VR, Phase DM, Choudhary RJ. Light-Controlled Magnetoelastic Effects in Ni/BaTiO 3 Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2023; 15:18391-18401. [PMID: 37010892 DOI: 10.1021/acsami.2c21948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Magnetoelastic and magnetoelectric coupling in the artificial multiferroic heterostructures facilitate valuable features for device applications such as magnetic field sensors and electric-write magnetic-read memory devices. In ferromagnetic/ferroelectric heterostructures, the intertwined physical properties can be manipulated by an external perturbation, such as an electric field, temperature, or a magnetic field. Here, we demonstrate the remote-controlled tunability of these effects under visible, coherent, and polarized light. The combined surface and bulk magnetic study of domain-correlated Ni/BaTiO3 heterostructures reveals that the system shows strong sensitivity to the light illumination via the combined effect of piezoelectricity, ferroelectric polarization, spin imbalance, magnetostriction, and magnetoelectric coupling. A well-defined ferroelastic domain structure is fully transferred from a ferroelectric substrate to the magnetostrictive layer via interface strain transfer. The visible light illumination is used to manipulate the original ferromagnetic microstructure by the light-induced domain wall motion in ferroelectric substrates and consequently the domain wall motion in the ferromagnetic layer. Our findings mimic the attractive remote-controlled ferroelectric random-access memory write and magnetic random-access memory read application scenarios, hence facilitating a perspective for room temperature spintronic device applications.
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Affiliation(s)
- Anita Bagri
- UGC-DAE Consortium for Scientific Research, Indore 452001, India
| | - Anupam Jana
- UGC-DAE Consortium for Scientific Research, Indore 452001, India
| | - Gyanendra Panchal
- Department Methods for Characterization of Transport Phenomena in Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
| | - Sourav Chowdhury
- UGC-DAE Consortium for Scientific Research, Indore 452001, India
| | - Rakhul Raj
- UGC-DAE Consortium for Scientific Research, Indore 452001, India
| | - Manish Kumar
- Pohang Accelerator Laboratory, POSTECH, Pohang 37673, South Korea
| | - Mukul Gupta
- UGC-DAE Consortium for Scientific Research, Indore 452001, India
| | | | | | - Ram J Choudhary
- UGC-DAE Consortium for Scientific Research, Indore 452001, India
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3
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Realization of macroscopic ratchet effect based on nonperiodic and uneven potentials. Sci Rep 2021; 11:16617. [PMID: 34400750 PMCID: PMC8368205 DOI: 10.1038/s41598-021-96192-z] [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: 03/25/2021] [Accepted: 08/04/2021] [Indexed: 11/28/2022] Open
Abstract
Ratchet devices allow turning an ac input signal into a dc output signal. A ratchet device is set by moving particles driven by zero averages forces on asymmetric potentials. Hybrid nanostructures combining artificially fabricated spin ice nanomagnet arrays with superconducting films have been identified as a good choice to develop ratchet nanodevices. In the current device, the asymmetric potentials are provided by charged Néel walls located in the vertices of spin ice magnetic honeycomb array, whereas the role of moving particles is played by superconducting vortices. We have experimentally obtained ratchet effect for different spin ice I configurations and for vortex lattice moving parallel or perpendicular to magnetic easy axes. Remarkably, the ratchet magnitudes are similar in all the experimental runs; i. e. different spin ice I configurations and in both relevant directions of the vortex lattice motion. We have simulated the interplay between vortex motion directions and a single asymmetric potential. It turns out vortices interact with uneven asymmetric potentials, since they move with trajectories crossing charged Néel walls with different orientations. Moreover, we have found out the asymmetric pair potentials which generate the local ratchet effect. In this rocking ratchet the particles (vortices) on the move are interacting each other (vortex lattice); therefore, the ratchet local effect turns into a global macroscopic effect. In summary, this ratchet device benefits from interacting particles moving in robust and topological protected type I spin ice landscapes.
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4
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Rubio-Marcos F, Del Campo A, Ordoñez-Pimentel J, Venet M, Rojas-Hernandez RE, Páez-Margarit D, Ochoa DA, Fernández JF, García JE. Photocontrolled Strain in Polycrystalline Ferroelectrics via Domain Engineering Strategy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:20858-20864. [PMID: 33881295 PMCID: PMC8480775 DOI: 10.1021/acsami.1c03162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
The use of photonic concepts to achieve nanoactuation based on light triggering requires complex architectures to obtain the desired effect. In this context, the recent discovery of reversible optical control of the domain configuration in ferroelectrics offers a light-ferroic interplay that can be easily controlled. To date, however, the optical control of ferroelectric domains has been explored in single crystals, although polycrystals are technologically more desirable because they can be manufactured in a scalable and reproducible fashion. Here we report experimental evidence for a large photostrain response in polycrystalline BaTiO3 that is comparable to their electrostrain values. Domains engineering is performed through grain size control, thereby evidencing that charged domain walls appear to be the functional interfaces for the light-driven domain switching. The findings shed light on the design of high-performance photoactuators based on ferroelectric ceramics, providing a feasible alternative to conventional voltage-driven nanoactuators.
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Affiliation(s)
- Fernando Rubio-Marcos
- Department
of Electroceramics, Instituto de Cerámica
y Vidrio, CSIC, Madrid 28049, Spain
| | - Adolfo Del Campo
- Department
of Electroceramics, Instituto de Cerámica
y Vidrio, CSIC, Madrid 28049, Spain
| | - Jonathan Ordoñez-Pimentel
- Department
of Physics, Universitat Politècnica
de Catalunya, BarcelonaTech, Barcelona 08034, Spain
- Department
of Physics, Universidade Federal de Sao
Carlos, Sao Carlos 13565-905, Brazil
| | - Michel Venet
- Department
of Physics, Universidade Federal de Sao
Carlos, Sao Carlos 13565-905, Brazil
| | | | - David Páez-Margarit
- Department
of Physics, Universitat Politècnica
de Catalunya, BarcelonaTech, Barcelona 08034, Spain
| | - Diego A. Ochoa
- Department
of Physics, Universitat Politècnica
de Catalunya, BarcelonaTech, Barcelona 08034, Spain
| | - José F. Fernández
- Department
of Electroceramics, Instituto de Cerámica
y Vidrio, CSIC, Madrid 28049, Spain
| | - Jose E. García
- Department
of Physics, Universitat Politècnica
de Catalunya, BarcelonaTech, Barcelona 08034, Spain
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5
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Luque LM, Grigera SA, Albano EV. Interfacial segregation of interacting vacancies and their role on the wetting critical properties of the Blume-Emery-Griffiths model. Phys Rev E 2021; 103:052803. [PMID: 34134273 DOI: 10.1103/physreve.103.052803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/28/2021] [Indexed: 06/12/2023]
Abstract
We study the wetting critical behavior of the three-state (s=±1,0) Blume-Emery-Griffiths model using numerical simulations. This model provides a suitable scenario for the study of the role of vacancies on the wetting behavior of a thin magnetic film. To this aim we study a system confined between parallel walls with competitive short-range surface magnetic fields (h_{L}=-|h_{1}|). We locate relevant critical curves for different values of the biquadratic interaction and use a thermodynamic integration method to calculate the surface tension as well as the interfacial excess energy and determine the wetting transition. Furthermore, we also calculate the local position of the interface along the film and its fluctuations (capillary waves), which are a measure of the interface width. To characterize the role played by vacancies on the interfacial behavior we evaluate the excess density of vacancies, i.e., the density difference between a system with and without interface. We also show that the temperature dependence of both the local position of the interface and its width can be rationalized in term of a finite-size scaling description, and we propose and successfully test the same scaling behavior for the average position of the center of mass of the vacancies and its fluctuations. This shows that the excess of vacancies can be associated to the presence of the interface that causes the observed segregation. This segregation phenomena is also evidenced by explicitly evaluating the interfacial free energy.
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Affiliation(s)
- L M Luque
- Instituto de Física de Líquidos y Sistemas Biológicos, UNLP-CONICET, La Plata 1900, Argentina
| | - S A Grigera
- Instituto de Física de Líquidos y Sistemas Biológicos, UNLP-CONICET, La Plata 1900, Argentina
| | - E V Albano
- Instituto de Física de Líquidos y Sistemas Biológicos, UNLP-CONICET, La Plata 1900, Argentina
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6
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Kolton AB, Jagla EA. Thermally rounded depinning of an elastic interface on a washboard potential. Phys Rev E 2020; 102:052120. [PMID: 33327099 DOI: 10.1103/physreve.102.052120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/27/2020] [Indexed: 11/07/2022]
Abstract
The thermal rounding of the depinning transition of an elastic interface sliding on a washboard potential is studied through analytic arguments and very accurate numerical simulations. We confirm the standard view that well below the depinning threshold the average velocity can be calculated considering thermally activated nucleation of defects. However, we find that the straightforward extension of this analysis to near or above the depinning threshold does not fully describe the physics of the thermally assisted motion. In particular, we find that exactly at the depinning point the average velocity does not follow a pure power law of the temperature as naively expected by the analogy with standard phase transitions but presents subtle logarithmic corrections. We explain the physical mechanisms behind these corrections and argue that they are nonpeculiar collective effects which may also apply to the case of interfaces sliding on uncorrelated disordered landscapes.
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Affiliation(s)
- A B Kolton
- Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, CNEA, CONICET, UNCUYO, Av. Bustillo 9500 R8402AGP S. C. de Bariloche, Río Negro, Argentina
| | - E A Jagla
- Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, CNEA, CONICET, UNCUYO, Av. Bustillo 9500 R8402AGP S. C. de Bariloche, Río Negro, Argentina
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7
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Rollano V, Muñoz-Noval A, Gomez A, Valdes-Bango F, Martin JI, Velez M, Osorio MR, Granados D, Gonzalez EM, Vicent JL. Topologically protected superconducting ratchet effect generated by spin-ice nanomagnets. NANOTECHNOLOGY 2019; 30:244003. [PMID: 30790770 DOI: 10.1088/1361-6528/ab0923] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We have designed, fabricated and tested a robust superconducting ratchet device based on topologically frustrated spin ice nanomagnets. The device is made of a magnetic Co honeycomb array embedded in a superconducting Nb film. This device is based on three simple mechanisms: (i) the topology of the Co honeycomb array frustrates in-plane magnetic configurations in the array yielding a distribution of magnetic charges which can be ordered or disordered with in-plane magnetic fields, following spin ice rules; (ii) the local vertex magnetization, which consists of a magnetic half vortex with two charged magnetic Néel walls; (iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Néel walls. The combination of these elements leads to a superconducting ratchet effect. Thus, superconducting vortices driven by alternating forces and moving on magnetic half vortices generate a unidirectional net vortex flow. This ratchet effect is independent of the distribution of magnetic charges in the array.
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Affiliation(s)
- V Rollano
- IMDEA-Nanociencia, Cantoblanco, E-28049 Madrid, Spain
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8
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Rubio-Marcos F, Páez-Margarit D, Ochoa DA, Del Campo A, Fernández JF, García JE. Photo-Controlled Ferroelectric-Based Nanoactuators. ACS APPLIED MATERIALS & INTERFACES 2019; 11:13921-13926. [PMID: 30938502 DOI: 10.1021/acsami.9b01628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Finding a feasible principle for a future generation of nano-optomechanical systems is a matter of intensive research, because it may provide new device prospects for optoelectronics and nanomanipulation techniques. Here we show that the strain of a ferroelectric crystal can be manipulated to achieve macroscopic, stable, and reproducible dimensional changes using illumination with photon energy below the material bandgap. The photoresponse can be activated without direct light incidence on the actuation area, because the cooperative nature of the phenomenon extends the photoinduced strain to the whole material. These results may be useful for developing the next generation of high-efficiency photocontrolled ferroelectric devices.
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Affiliation(s)
- Fernando Rubio-Marcos
- Department of Electroceramics , Instituto de Cerámica y Vidrio (CSIC) , Madrid 28049 , Spain
| | - David Páez-Margarit
- Department of Physics , Universitat Politècnica de Catalunya-BarcelonaTech , Barcelona 08034 , Spain
| | - Diego A Ochoa
- Department of Physics , Universitat Politècnica de Catalunya-BarcelonaTech , Barcelona 08034 , Spain
| | - Adolfo Del Campo
- Department of Electroceramics , Instituto de Cerámica y Vidrio (CSIC) , Madrid 28049 , Spain
| | - José F Fernández
- Department of Electroceramics , Instituto de Cerámica y Vidrio (CSIC) , Madrid 28049 , Spain
| | - José E García
- Department of Physics , Universitat Politècnica de Catalunya-BarcelonaTech , Barcelona 08034 , Spain
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9
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Bran C, Berganza E, Fernandez-Roldan JA, Palmero EM, Meier J, Calle E, Jaafar M, Foerster M, Aballe L, Fraile Rodriguez A, P Del Real R, Asenjo A, Chubykalo-Fesenko O, Vazquez M. Magnetization Ratchet in Cylindrical Nanowires. ACS NANO 2018; 12:5932-5939. [PMID: 29812903 DOI: 10.1021/acsnano.8b02153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The unidirectional motion of information carriers such as domain walls in magnetic nanostrips is a key feature for many future spintronic applications based on shift registers. This magnetic ratchet effect has so far been achieved in a limited number of complex nanomagnetic structures, for example, by lithographically engineered pinning sites. Here we report on a simple remagnetization ratchet originated in the asymmetric potential from the designed increasing lengths of magnetostatically coupled ferromagnetic segments in FeCo/Cu cylindrical nanowires. The magnetization reversal in neighboring segments propagates sequentially in steps starting from the shorter segments, irrespective of the applied field direction. This natural and efficient ratchet offers alternatives for the design of three-dimensional advanced storage and logic devices.
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Affiliation(s)
- Cristina Bran
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | - Eider Berganza
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | | | - Ester M Palmero
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | - Jessica Meier
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | - Esther Calle
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | - Miriam Jaafar
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | - Michael Foerster
- ALBA Synchrotron Light Facility, CELLS , 08290 Barcelona , Spain
| | - Lucia Aballe
- ALBA Synchrotron Light Facility, CELLS , 08290 Barcelona , Spain
| | | | - Rafael P Del Real
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | - Agustina Asenjo
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
| | | | - Manuel Vazquez
- Institute of Materials Science of Madrid, CSIC , 28049 Madrid , Spain
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10
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Caballero NB, Ferrero EE, Kolton AB, Curiale J, Jeudy V, Bustingorry S. Magnetic domain wall creep and depinning: A scalar field model approach. Phys Rev E 2018; 97:062122. [PMID: 30011479 DOI: 10.1103/physreve.97.062122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Indexed: 06/08/2023]
Abstract
Magnetic domain wall motion is at the heart of new magnetoelectronic technologies and hence the need for a deeper understanding of domain wall dynamics in magnetic systems. In this context, numerical simulations using simple models can capture the main ingredients responsible for the complex observed domain wall behavior. We present a scalar field model for the magnetization dynamics of quasi-two-dimensional systems with a perpendicular easy axis of magnetization which allows a direct comparison with typical experimental protocols, used in polar magneto-optical Kerr effect microscopy experiments. We show that the thermally activated creep and depinning regimes of domain wall motion can be reached and the effect of different quenched disorder implementations can be assessed with the model. In particular, we show that the depinning field increases with the mean grain size of a Voronoi tessellation model for the disorder.
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Affiliation(s)
- Nirvana B Caballero
- CONICET, Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
| | - Ezequiel E Ferrero
- CONICET, Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
| | - Alejandro B Kolton
- CONICET, Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
- Instituto Balseiro, Universidad Nacional de Cuyo, CNEA, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
| | - Javier Curiale
- CONICET, Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
- Instituto Balseiro, Universidad Nacional de Cuyo, CNEA, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
| | - Vincent Jeudy
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Sebastian Bustingorry
- CONICET, Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro, Argentina
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11
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Dobrovolskiy OV, Huth M, Shklovskij VA, Vovk RV. Mobile fluxons as coherent probes of periodic pinning in superconductors. Sci Rep 2017; 7:13740. [PMID: 29062080 PMCID: PMC5653780 DOI: 10.1038/s41598-017-14232-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 10/06/2017] [Indexed: 11/17/2022] Open
Abstract
The interaction of (quasi)particles with a periodic potential arises in various domains of science and engineering, such as solid-state physics, chemical physics, and communication theory. An attractive test ground to investigate this interaction is represented by superconductors with artificial pinning sites, where magnetic flux quanta (Abrikosov vortices) interact with the pinning potential U(r) = U(r + R) induced by a nanostructure. At a combination of microwave and dc currents, fluxons act as mobile probes of U(r): The ac component shakes the fluxons in the vicinity of their equilibrium points which are unequivocally determined by the local pinning force counterbalanced by the Lorentz force induced by the dc current, linked to the curvature of U(r) which can then be used for a successful fitting of the voltage responses. A good correlation of the deduced dependences U(r) with the cross sections of the nanostructures points to that pinning is primarily caused by vortex length reduction. Our findings pave a new route to a non-destructive evaluation of periodic pinning in superconductor thin films. The approach should also apply to a broad class of systems whose evolution in time can be described by the coherent motion of (quasi)particles in a periodic potential.
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Affiliation(s)
- Oleksandr V Dobrovolskiy
- Physikalisches Institut, Goethe University, Frankfurt am Main, 60438, Germany. .,Physics Department, V. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine.
| | - Michael Huth
- Physikalisches Institut, Goethe University, Frankfurt am Main, 60438, Germany
| | - Valerij A Shklovskij
- Physics Department, V. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine
| | - Ruslan V Vovk
- Physics Department, V. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine
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12
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McDermott D, Olson Reichhardt CJ, Reichhardt C. Collective ratchet effects and reversals for active matter particles on quasi-one-dimensional asymmetric substrates. SOFT MATTER 2016; 12:8606-8615. [PMID: 27714306 DOI: 10.1039/c6sm01394e] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using computer simulations, we study a two-dimensional system of sterically interacting self-mobile run-and-tumble disk-shaped particles with an underlying periodic quasi-one-dimensional asymmetric substrate, and show that a rich variety of collective active ratchet behaviors arise as a function of particle density, activity, substrate period, and the maximum force exerted by the substrate. The net dc drift, or ratchet transport flux, is nonmonotonic since it increases with increased activity but is diminished by the onset of self-clustering of the active particles. Increasing the particle density decreases the ratchet transport flux for shallow substrates but increases the ratchet transport flux for deep substrates due to collective hopping events. At the highest particle densities, the ratchet motion is destroyed by a self-jamming effect. We show that it is possible to realize reversals of the direction of the net dc drift in the deep substrate limit when multiple rows of active particles can be confined in each substrate minimum, permitting emergent particle-like excitations to appear that experience an inverted effective substrate potential. We map out a phase diagram of the forward and reverse ratchet effects as a function of the particle density, activity, and substrate properties.
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Affiliation(s)
- Danielle McDermott
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. and Department of Physics, Wabash College, Crawfordsville, Indiana 47933, USA
| | | | - Charles Reichhardt
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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13
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Trobo ML, Albano EV. Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:125001. [PMID: 26910650 DOI: 10.1088/0953-8984/28/12/125001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Fixed vacancies (non-magnetic impurities) are placed along the centre of Ising strips in order to study the wetting behaviour in this confined system, by means of numerical simulations analysed with the aid of finite size scaling and thermodynamic integration methods. By considering strips of size L × M (L << M) where short-range competitive surface fields (H(s)) act along the M-direction, we observe localization-delocalization transitions of the interface between magnetic domains of different orientation (driven by the corresponding surface fields), which are the precursors of the wetting transitions that occur in the thermodynamic limit. By placing vacancies or equivalently non-magnetic impurities along the centre of the sample, we found that for low vacancy densities the wetting transitions are of second order, while by increasing the concentration of vacancies the transitions become of first order. Second- and first-order lines meet in tricritical wetting points (H(tric)(SW), T(tric)(W)), where H(tric)(SW) and T(Tric)(W) are the magnitude of the surface field and the temperature, respectively. In the phase diagram, tricritical points shift from the high temperature and weak surface field regime at large vacancy densities to the T --> 0, H(tric)(SW) --> 1 limit for low vacancy densities. By comparing the locations of the tricritical points with those corresponding to the case of mobile impurities, we conclude that in order to observe similar effects, in the latter the required density of impurities is much smaller (e.g. by a factor 3-5). Furthermore, a proper density of non magnetic impurities placed along the centre of a strip can effectively pin rather flat magnetic interfaces for suitable values of the competing surface fields and temperature.
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Affiliation(s)
- Marta L Trobo
- Instituto de Física de Líquidos y Sistemas Biológicos (IFLYSIB), CCT-CONICET La Plata, UNLP, Calle 59 Nro. 789, (1900) La Plata, Argentina. Departamento de Ciencias Básicas, Facultad de Ingeniería, Universidad Nacional de La Plata, B1900AWN La Plata, Buenos Aires, Argentina
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14
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Hierro-Rodriguez A, Teixeira JM, Rodriguez-Rodriguez G, Rubio H, Vélez M, Álvarez-Prado LM, Martín JI, Alameda JM. Unravelling the tunable exchange bias-like effect in magnetostatically-coupled two dimensional hybrid (hard/soft) composites. NANOTECHNOLOGY 2015; 26:225302. [PMID: 25966296 DOI: 10.1088/0957-4484/26/22/225302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Hybrid 2D hard-soft composites have been fabricated by combining soft (Co73Si27) and hard (NdCo5) magnetic materials with in-plane and out-of-plane magnetic anisotropies, respectively. They have been microstructured in a square lattice of CoSi anti-dots with NdCo dots within the holes. The magnetic properties of the dots allow us to introduce a magnetostatic stray field that can be controlled in direction and sense by their last saturating magnetic field. The magnetostatic interactions between dot and anti-dot layers induce a completely tunable exchange bias-like shift in the system's hysteresis loops. Two different regimes for this shift are present depending on the lattice parameter of the microstructures. For large parameters, dipolar magnetostatic decay is observed, while for the smaller one, the interaction between the adjacent anti-dot's characteristic closure domain structures enhances the exchange bias-like effect as clarified by micromagnetic simulations.
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Affiliation(s)
- A Hierro-Rodriguez
- IFIMUP and IN, Institute of Nanoscience and Nanotechnology, Rua do Campo Alegre, 4169-007 Porto, Portugal. INESC-TEC (Coordinated by INESC-Porto), Rua do Campo Alegre, 4169-007 Porto, Portugal
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15
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Trobo ML, Albano EV, Binder K. First-order and tricritical wetting transitions in the two-dimensional Ising model caused by interfacial pinning at a defect line. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:022406. [PMID: 25215741 DOI: 10.1103/physreve.90.022406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Indexed: 06/03/2023]
Abstract
We present a study of the critical behavior of the Blume-Capel model with three spin states (S=±1,0) confined between parallel walls separated by a distance L where competitive surface magnetic fields act. By properly choosing the crystal field (D), which regulates the density of nonmagnetic species (S=0), such that those impurities are excluded from the bulk (where D=-∞) except in the middle of the sample [where D(M)(L/2)≠-∞], we are able to control the presence of a defect line in the middle of the sample and study its influence on the interface between domains of different spin orientations. So essentially we study an Ising model with a defect line but, unlike previous work where defect lines in Ising models were defined via weakened bonds, in the present case the defect line is due to mobile vacancies and hence involves additional entropy. In this way, by drawing phase diagrams, i.e., plots of the wetting critical temperature (T(w)) versus the magnitude of the crystal field at the middle of the sample (D(M)), we observe curves of (first-) second-order wetting transitions for (small) high values of D(M). Theses lines meet in tricritical wetting points, i.e., (T(w)(tc),D(M)(tc)), which also depend on the magnitude of the surface magnetic fields. It is found that second-order wetting transitions satisfy the scaling theory for short-range interactions, while first-order ones do not exhibit hysteresis, provided that small samples are used, since fluctuations wash out hysteretic effects. Since hysteresis is observed in large samples, we performed extensive thermodynamic integrations in order to accurately locate the first-order transition points, and a rather good agreement is found by comparing such results with those obtained just by observing the jump of the order parameter in small samples.
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Affiliation(s)
- Marta L Trobo
- Instituto de Física de Líquidos y Sistemas Biológicos (IFLYSIB), CCT-CONICET La Plata, UNLP. Calle 59 Nro. 789, (1900) La Plata, Argentina and Facultad de Ingeniería, Universidad Nacional de La Plata, Argentina
| | - Ezequiel V Albano
- Instituto de Física de Líquidos y Sistemas Biológicos (IFLYSIB), CCT-CONICET La Plata, UNLP. Calle 59 Nro. 789, (1900) La Plata, Argentina and Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
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Shklovskij VA, Sosedkin VV, Dobrovolskiy OV. Vortex ratchet reversal in an asymmetric washboard pinning potential subject to combined dc and ac stimuli. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:025703. [PMID: 24304564 DOI: 10.1088/0953-8984/26/2/025703] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The mixed-state resistive response of a superconductor thin film with an asymmetric washboard pinning potential subject to superimposed dc and ac currents of arbitrary amplitudes and frequency at finite temperature is theoretically investigated. The problem is considered in the single-vortex approximation, relying upon the exact solution of the Langevin equation in terms of a matrix continued fraction. The dc voltage response and the absorbed power in ac response are analyzed as functions of dc bias and ac current amplitude and frequency in a wide range of corresponding dimensionless parameters. Predictions are made of (i) a reversal of the rectified voltage at small dc biases and strong ac drives and (ii) a non-monotonic enhancement of the absorbed power in the nonlinear ac response at far sub-depinning frequencies. It is elucidated how and why both these effects appear due to the competition of the fixed internal and the tunable, dc bias-induced external asymmetry of the potential as the only reason. This is distinct from other scenarios used for explaining the vortex ratchet reversal effect so far.
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Affiliation(s)
- Valerij A Shklovskij
- Institute of Theoretical Physics, NSC-KIPT, 61108 Kharkiv, Ukraine. Physical Department, Kharkiv National University, 61077 Kharkiv, Ukraine
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Franken JH, Swagten HJM, Koopmans B. Shift registers based on magnetic domain wall ratchets with perpendicular anisotropy. NATURE NANOTECHNOLOGY 2012; 7:499-503. [PMID: 22796743 DOI: 10.1038/nnano.2012.111] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 06/01/2012] [Indexed: 06/01/2023]
Abstract
The movement of magnetic domain walls can be used to build a device known as a shift register, which has applications in memory and logic circuits. However, the application of magnetic domain wall shift registers has been hindered by geometrical restrictions, by randomness in domain wall displacement and by the need for high current densities or rotating magnetic fields. Here, we propose a new approach in which the energy landscape experienced by the domain walls is engineered to favour a unidirectional ratchet-like propagation. The domain walls are defined between domains with an out-of-plane (perpendicular) magnetization, which allows us to route domain walls along arbitrary in-plane paths using a time-varying applied magnetic field with fixed orientation. In addition, this ratchet-like motion causes the domain walls to lock to discrete positions along these paths, which is useful for digital devices. As a proof-of-principle experiment we demonstrate the continuous propagation of two domain walls along a closed-loop path in a platinum/cobalt/platinum strip.
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Affiliation(s)
- J H Franken
- Department of Applied Physics, Center for NanoMaterials, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
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18
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Cotes SM, Albano EV. First- and second-order wetting transitions in confined Ising films in the presence of nonmagnetic impurities: a Monte Carlo simulation study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:061105. [PMID: 21797300 DOI: 10.1103/physreve.83.061105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 04/15/2011] [Indexed: 05/31/2023]
Abstract
In this work, we present the results of a systematic exploration of the effect caused by the introduction of nonmagnetic impurities (or defects) on the stabilization of the interface between two magnetic domains of opposite magnetic orientation. Those defects are simulated as spin vacancies along the center of confined two-dimensional Ising films, which have competing magnetic fields acting on the confinement walls. The calculations are performed for different L×M film sizes and by using the standard Metropolis dynamics. In the absence of defects, the film is characterized by an interface running along the M direction, which is induced by the competing surface fields. That interface undergoes a localization-delocalization transition that is the precursor of a true wetting transition taking place in the thermodynamic limit. When the density of defects is relatively low, our results show that the wetting phase transition is of second order, as in the absence of defects. On the other hand, when the density of nonmagnetic impurities is relatively high, a pinning effect of the interface gives rise to a first-order wetting phase transition. The observed transitions are characterized by measuring relevant properties, such as magnetization profiles, cumulants, magnetization fluctuations, etc., as a function of the density of defects. So, our main finding is that the presence of nonmagnetic impurities introduces a rich physical scenery, such as a line of second-order wetting transitions (observed for low density of defects) that merges into a first-order one just at a tricritical point. Precisely, these two latter findings are the major contributions of our study.
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Affiliation(s)
- S M Cotes
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT-La Plata CONICET, La Plata, Argentina.
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Tierno P, Reimann P, Johansen TH, Sagués F. Giant transversal particle diffusion in a longitudinal magnetic ratchet. PHYSICAL REVIEW LETTERS 2010; 105:230602. [PMID: 21231443 DOI: 10.1103/physrevlett.105.230602] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Indexed: 05/30/2023]
Abstract
We study the transversal motion of paramagnetic particles on a uniaxial garnet film, exhibiting a longitudinal ratchet effect in the presence of an oscillating magnetic field. Without the field, the thermal diffusion coefficient obtained by video microscopy is D(0) ≈ 3 × 10(-4) μm2/s. With the field, the transversal diffusion exhibits a giant enhancement by almost four decades and a pronounced maximum as a function of the driving frequency. We explain the experimental findings with a theoretical interpretation in terms of random disorder effects within the magnetic film.
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Affiliation(s)
- Pietro Tierno
- Departament de Química Física, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
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Zapata I, Albaladejo S, Parrondo JMR, Sáenz JJ, Sols F. Deterministic ratchet from stationary light fields. PHYSICAL REVIEW LETTERS 2009; 103:130601. [PMID: 19905498 DOI: 10.1103/physrevlett.103.130601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Indexed: 05/28/2023]
Abstract
Ratchets are dynamic systems where particle transport is induced by zero-average forces due to the interplay between nonlinearity and asymmetry. Generally, they rely on the effect of a strong external driving. We show that stationary optical lattices can be designed to generate particle flow in one direction while requiring neither noise nor driving. Such optical fields must be arranged to yield a combination of conservative (dipole) and nonconservative (radiation pressure) forces. Under strong friction all paths converge to a discrete set of limit periodic trajectories flowing in the same direction.
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Affiliation(s)
- I Zapata
- Departamento Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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Zarlenga DG, Larrondo HA, Arizmendi CM, Family F. Complex synchronization structure of an overdamped ratchet with discontinuous periodic forcing. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:011127. [PMID: 19658673 DOI: 10.1103/physreve.80.011127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Indexed: 05/28/2023]
Abstract
A deterministic overdamped ratchet driven by a periodic square driving force is shown to display chaotic behavior. The system has neither temporal nor quenched noise but the strong nonlinearity of the driving force produces a very rich bifurcation pattern with synchronized as well as chaotic regions. This pattern disappears if a sinusoidal force replaces the square force. This unexpected behavior is explained by decomposing the system into two exactly solvable subsystems, each with its own characteristic transit time, so that the ratio between the period of the driving force and the transit times can be analyzed. The transition from synchronized to chaotic motion can be explained by means of a one-dimensional Poincaré map. Our results can be experimentally confirmed in a number of systems, including the three-junction superconducting quantum interference devices ratchet, the rocking ratchet effect for cold atoms, and the Josephson vortex ratchet.
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Affiliation(s)
- D G Zarlenga
- Departamento de Física, Facultad de Ingeniería, Universidad Nacional de Mar del Plata, Avenida J.B. Justo 4302, 7600 Mar del Plata, Argentina
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