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Vélez S, Ruiz-Gómez S, Schaab J, Gradauskaite E, Wörnle MS, Welter P, Jacot BJ, Degen CL, Trassin M, Fiebig M, Gambardella P. Current-driven dynamics and ratchet effect of skyrmion bubbles in a ferrimagnetic insulator. NATURE NANOTECHNOLOGY 2022; 17:834-841. [PMID: 35788187 DOI: 10.1038/s41565-022-01144-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Magnetic skyrmions are compact chiral spin textures that exhibit a rich variety of topological phenomena and hold potential for the development of high-density memory devices and novel computing schemes driven by spin currents. Here, we demonstrate the room-temperature interfacial stabilization and current-driven control of skyrmion bubbles in the ferrimagnetic insulator Tm3Fe5O12 coupled to Pt, showing the current-induced motion of individual skyrmion bubbles. The ferrimagnetic order of the crystal together with the interplay of spin-orbit torques and pinning determine the skyrmion dynamics in Tm3Fe5O12 and result in a strong skyrmion Hall effect characterized by a negative deflection angle and hopping motion. Further, we show that the velocity and depinning threshold of the skyrmion bubbles can be modified by exchange coupling Tm3Fe5O12 to an in-plane magnetized Y3Fe5O12 layer, which distorts the spin texture of the skyrmions and leads to directional-dependent rectification of their dynamics. This effect, which is equivalent to a magnetic ratchet, is exploited to control the skyrmion flow in a racetrack-like device.
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Affiliation(s)
- Saül Vélez
- Department of Materials, ETH Zurich, Zurich, Switzerland.
- Condensed Matter Physics Center, Instituto Nicolás Cabrera, and Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain.
| | - Sandra Ruiz-Gómez
- Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid, Spain
- Alba Synchrotron Light Facility, Barcelona, Spain
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Jakob Schaab
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | | | | | - Pol Welter
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | | | | | - Morgan Trassin
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Manfred Fiebig
- Department of Materials, ETH Zurich, Zurich, Switzerland
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2
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Gao ZC, Su Y, Xi B, Hu J, Park C. The origin of spin wave pulse-induced domain wall inertia. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:475803. [PMID: 32870813 DOI: 10.1088/1361-648x/abae1a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
The fundamental problem of domain wall (DW) inertia-the property that gives to inertial behaviors remains unclear in the physics of magnetic solitons. To understand its nature as well as to achieve accurate DW positioning and efficient manipulation of domain wall motion (DWM), spin wave (SW) pulse-induced DW transient effect is studied both numerically and theoretically in a magnetic nanostrip. It is shown for the first time that there occurs inevitable deceleration/automotion after SW pulse, which indicates nonzero DW inertia. The induced DWM is revealed to relate to two factors: energy storing within DW and out-of-plane tilting of DW. To explain the DWM dynamics, a one-dimensional collective model is developed to account for the excitation of spin wave pulse. The model successfully bridges DW energy, DW tilting and DW displacement and provides descriptions in accordance with numerical findings. It is made clear that the DW automotion hence DW inertia originate from the process of DW relaxation toward equilibrium. The DW inertia is expressed in terms of effective mass and turns out to be a time-dependent function with damping constantαas the governing parameter, which opposes the nature of intrinsic mass. For case containing multiple DWs, the total effective mass is shown to concern the reached velocity and stored energy of DWs instead of the number of DWs, which is against common intuition.
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Affiliation(s)
- Zhong-Chen Gao
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225002, People's Republic of China
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Yuanchang Su
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225002, People's Republic of China
| | - Bin Xi
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225002, People's Republic of China
| | - Jingguo Hu
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225002, People's Republic of China
| | - Chan Park
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
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3
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Hurst HM, Galitski V, Heikkilä TT. Electron Induced Massive Dynamics of Magnetic Domain Walls. PHYSICAL REVIEW. B 2020; 101:10.1103/physrevb.101.054407. [PMID: 38567107 PMCID: PMC10986426 DOI: 10.1103/physrevb.101.054407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
We study the dynamics of domain walls (DWs) in a metallic, ferromagnetic nanowire, focusing on inertial effects on the DW due to interaction with a conduction electron bath. We develop a Keldysh collective coordinate technique to describe the effect of conduction electrons on rigid magnetic structures. The effective Lagrangian and Langevin equations of motion for a DW are derived microscopically, including the full response kernel which is nonlocal in time. The DW dynamics is described by two collective degrees of freedom: position and tilt-angle. The coupled Langevin equations therefore involve two correlated noise sources, leading to a generalized fluctuation-dissipation theorem (FDT). The DW response kernel due to electrons contains two parts: one related to dissipation via FDT, and another reactive part. We prove that the latter term leads to a mass for both degrees of freedom, even though the intrinsic bare mass is zero. The electron-induced mass is present even in a clean system without pinning or specifically engineered potentials. The resulting equations of motion contain rich dynamical solutions and point toward a way to control domain wall motion in metals via the electronic system properties. We discuss two observable consequences of the mass, hysteresis in the DW dynamics and resonant response to ac current.
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Affiliation(s)
- Hilary M Hurst
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, Maryland, 20899, USA
- Department of Physics and Astronomy, San José State University, San José, California, 95192, USA
| | - Victor Galitski
- Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Tero T Heikkilä
- Department of Physics and Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
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4
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Vélez S, Schaab J, Wörnle MS, Müller M, Gradauskaite E, Welter P, Gutgsell C, Nistor C, Degen CL, Trassin M, Fiebig M, Gambardella P. High-speed domain wall racetracks in a magnetic insulator. Nat Commun 2019; 10:4750. [PMID: 31628309 PMCID: PMC6802104 DOI: 10.1038/s41467-019-12676-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 09/23/2019] [Indexed: 11/21/2022] Open
Abstract
Recent reports of current-induced switching of ferrimagnetic oxides coupled to heavy metals have opened prospects for implementing magnetic insulators into electrically addressable devices. However, the configuration and dynamics of magnetic domain walls driven by electrical currents in insulating oxides remain unexplored. Here we investigate the internal structure of the domain walls in Tm3Fe5O12 (TmIG) and TmIG/Pt bilayers, and demonstrate their efficient manipulation by spin-orbit torques with velocities of up to 400 ms-1 and minimal current threshold for domain wall flow of 5 × 106 A cm-2. Domain wall racetracks are defined by Pt current lines on continuous TmIG films, which allows for patterning the magnetic landscape of TmIG in a fast and reversible way. Scanning nitrogen-vacancy magnetometry reveals that the domain walls of TmIG thin films grown on Gd3Sc2Ga3O12 exhibit left-handed Néel chirality, changing to an intermediate Néel-Bloch configuration upon Pt deposition. These results indicate the presence of interfacial Dzyaloshinskii-Moriya interaction in magnetic garnets, opening the possibility to stabilize chiral spin textures in centrosymmetric magnetic insulators.
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Affiliation(s)
- Saül Vélez
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.
| | - Jakob Schaab
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | - Martin S Wörnle
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
- Department of Physics, ETH Zurich, 8093, Zurich, Switzerland
| | - Marvin Müller
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | | | - Pol Welter
- Department of Physics, ETH Zurich, 8093, Zurich, Switzerland
| | | | - Corneliu Nistor
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | | | - Morgan Trassin
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.
| | - Manfred Fiebig
- Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.
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5
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Kato N, Kawaguchi M, Lau YC, Kikuchi T, Nakatani Y, Hayashi M. Current-Induced Modulation of the Interfacial Dzyaloshinskii-Moriya Interaction. PHYSICAL REVIEW LETTERS 2019; 122:257205. [PMID: 31347878 DOI: 10.1103/physrevlett.122.257205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 02/05/2019] [Indexed: 06/10/2023]
Abstract
The Dzyaloshinskii-Moriya (DM) interaction is an antisymmetric exchange interaction that is responsible for the emergence of chiral magnetism. The origin of the DM interaction, however, remains to be identified albeit the large number of studies reported on related effects. It has been recently suggested that the DM interaction is equivalent to an equilibrium spin current density originating from spin-orbit coupling, an effect referred to as the spin Doppler effect. The model predicts that the DM interaction can be controlled by spin current injected externally. Here we show that the DM exchange constant (D) in W/CoFeB-based heterostructures can be modulated with external current passed along the film plane. At higher current, D decreases with increasing current, which we infer is partly due to the adiabatic spin transfer torque. At lower current, D increases linearly with current regardless of the polarity of current flow. The rate of increase in D with the current density agrees with that predicted by the model based on the spin Doppler effect. These results imply that the DM interaction at the heavy-metal-ferromagnetic-metal interface partly originates from an equilibrium interface spin (polarized) current which can be modulated externally.
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Affiliation(s)
- Naoaki Kato
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
| | - Masashi Kawaguchi
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yong-Chang Lau
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Toru Kikuchi
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
| | | | - Masamitsu Hayashi
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- National Institute for Materials Science, Tsukuba 305-0047, Japan
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Finizio S, Wintz S, Zeissler K, Sadovnikov AV, Mayr S, Nikitov SA, Marrows CH, Raabe J. Dynamic Imaging of the Delay- and Tilt-Free Motion of Néel Domain Walls in Perpendicularly Magnetized Superlattices. NANO LETTERS 2019; 19:375-380. [PMID: 30517003 DOI: 10.1021/acs.nanolett.8b04091] [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
We report on the time-resolved investigation of current- and field-induced domain wall motion in the flow regime in perpendicularly magnetized microwires exhibiting antisymmetric exchange interaction by means of scanning transmission X-ray microscopy with a 200 ps time step. The sub-ns time step of the dynamical images allowed us to observe the absence of incubation times for the motion of the domain wall within an uncertainty of 200 ps, together with indications for a negligible inertia of the domain wall. Furthermore, we observed that, for short current and magnetic field pulses, the magnetic domain walls do not exhibit a tilting during their motion, providing a mechanism for the fast, tilt-free, current-induced motion of magnetic domain walls.
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Affiliation(s)
- Simone Finizio
- Swiss Light Source , Paul Scherrer Institut , 5232 Villigen PSI , Switzerland
| | - Sebastian Wintz
- Swiss Light Source , Paul Scherrer Institut , 5232 Villigen PSI , Switzerland
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , 01328 Dresden , Germany
| | - Katharina Zeissler
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Alexandr V Sadovnikov
- Laboratory Metamaterials , Saratov State University , Saratov 410012 , Russia
- Kotel'nikov Institute of Radioengineering and Electronics , Russian Academy of Sciences , Moscow 125009 , Russia
| | - Sina Mayr
- Swiss Light Source , Paul Scherrer Institut , 5232 Villigen PSI , Switzerland
- Department of Materials, Laboratory for Mesoscopic Systems , ETH Zürich , 8093 Zürich , Switzerland
| | - Sergey A Nikitov
- Laboratory Metamaterials , Saratov State University , Saratov 410012 , Russia
- Kotel'nikov Institute of Radioengineering and Electronics , Russian Academy of Sciences , Moscow 125009 , Russia
| | - Christopher H Marrows
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Jörg Raabe
- Swiss Light Source , Paul Scherrer Institut , 5232 Villigen PSI , Switzerland
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7
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Moon KW, Kim C, Yoon J, Choi JW, Kim DO, Song KM, Kim D, Chun BS, Hwang C. A spin torque meter with magnetic facet domains. Nat Commun 2018; 9:3788. [PMID: 30224700 PMCID: PMC6141574 DOI: 10.1038/s41467-018-06223-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 08/24/2018] [Indexed: 11/23/2022] Open
Abstract
Current-induced magnetic domain wall (DW) motion is an important operating principle of spintronic devices. Injected current generates spin torques (STs) on the DWs in two ways. One is the spin transfer from magnetic domains to the walls by the current flowing in the magnet. Current flow in attached heavy metals also generates another ST because of the spin-Hall effect. Both phenomena explain the wall motions well; therefore, their respective contribution is an important issue. Here, we show the simultaneous measurement of both torques by using magnetic facet domains that form mountain-shaped domains with straight walls. When the STs and the external magnetic field push the walls in opposite directions, the walls should have equilibrium angles to create balanced states. Such angles can be modulated by an additional in-plane magnetic field. Angle measurements distinguish the STs because each torque has a distinct mechanism related to the DW structure.
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Affiliation(s)
- Kyoung-Woong Moon
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Changsoo Kim
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jungbum Yoon
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jun Woo Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Dong-Ok Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
- Department of Physics, Soongsil University, Seoul, 06978, Republic of Korea
| | - Kyung Mee Song
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
- Department of Physics, Sookmyung Women's University, Seoul, 04130, Republic of Korea
| | - Dongseuk Kim
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Byong Sun Chun
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Chanyong Hwang
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea.
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Garg C, Pushp A, Yang SH, Phung T, Hughes BP, Rettner C, Parkin SSP. Highly Asymmetric Chiral Domain-Wall Velocities in Y-Shaped Junctions. NANO LETTERS 2018; 18:1826-1830. [PMID: 29420900 DOI: 10.1021/acs.nanolett.7b05086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recent developments in spin-orbit torques allow for highly efficient current-driven domain wall (DW) motion in nanowires with perpendicular magnetic anisotropy. Here, we show that chiral DWs can be driven into nonequilibrium states that can persist over tens of nanoseconds in Y-shaped magnetic nanowire junctions that have an input and two symmetric outputs. A single DW that is injected into the input splits and travels at very different velocities in the two output branches until it reaches its steady-state velocity. We find that this is due to the disparity between the fast temporal evolution of the spin current derived spin-orbit torque and a much-slower temporal evolution of the DMI-derived torque. Changing the DW polarity inverts the velocity asymmetry in the two output branches, a property that we use to demonstrate the sorting of domains.
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Affiliation(s)
- Chirag Garg
- IBM Research, Almaden , San Jose , California 95120 , United States
- Max Planck Institute of Microstructure Physics , Halle (Saale) D06120 , Germany
- Institute of Physics , Martin Luther University Halle-Wittenberg , Halle (Saale) D06120 , Germany
| | - Aakash Pushp
- IBM Research, Almaden , San Jose , California 95120 , United States
| | - See-Hun Yang
- IBM Research, Almaden , San Jose , California 95120 , United States
| | - Timothy Phung
- IBM Research, Almaden , San Jose , California 95120 , United States
| | - Brian P Hughes
- IBM Research, Almaden , San Jose , California 95120 , United States
| | - Charles Rettner
- IBM Research, Almaden , San Jose , California 95120 , United States
| | - Stuart S P Parkin
- IBM Research, Almaden , San Jose , California 95120 , United States
- Max Planck Institute of Microstructure Physics , Halle (Saale) D06120 , Germany
- Institute of Physics , Martin Luther University Halle-Wittenberg , Halle (Saale) D06120 , Germany
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Efficient and controlled domain wall nucleation for magnetic shift registers. Sci Rep 2017; 7:11909. [PMID: 28928378 PMCID: PMC5605553 DOI: 10.1038/s41598-017-12230-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/06/2017] [Indexed: 11/08/2022] Open
Abstract
Ultrathin ferromagnetic strips with high perpendicular anisotropy have been proposed for the development of memory devices where the information is coded in tiny domains separated by domain walls. The design of practical devices requires creating, manipulating and detecting domain walls in ferromagnetic strips. Recent observations have shown highly efficient current-driven domain wall dynamics in multilayers lacking structural symmetry, where the walls adopt a chiral structure and can be driven at high velocities. However, putting such a device into practice requires the continuous and synchronous injection of domain walls as the first step. Here, we propose and demonstrate an efficient and simple scheme for nucleating domain walls using the symmetry of the spin orbit torques. Trains of short sub-nanosecond current pulses are injected in a double bit line to generate a localized longitudinal Oersted field in the ferromagnetic strip. Simultaneously, other current pulses are injected through the heavy metal under the ferromagnetic strip. Notably, the Slonczewski-like spin orbit torque assisted by the Oersted field allows the controlled injection of a series of domain walls, giving rise to a controlled manner for writing binary information and, consequently, to the design of a simple and efficient domain wall shift register.
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Competition between Superconductor - Ferromagnetic stray magnetic fields in YBa 2Cu 3O 7-x films pierced with Co nano-rods. Sci Rep 2017; 7:5663. [PMID: 28720833 PMCID: PMC5516025 DOI: 10.1038/s41598-017-05909-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 06/05/2017] [Indexed: 11/09/2022] Open
Abstract
Superconductivity and ferromagnetism are two antagonistic phenomena that combined can lead to a rich phenomenology of interactions, resulting in novel physical properties and unique functionalities. Here we propose an original hybrid system formed by a high-temperature superconducting film, patterned with antidots, and with ferromagnetic nano-rods grown inside them. This particular structure exhibits the synergic influence of superconductor (SC) - ferromagnetic (FM) stray fields, in both the superconducting behaviour of the film and the three-dimensional (3D) magnetic structure of nano-rods. We show that FM stray fields directly influence the critical current density of the superconducting film. Additional functionalities appear due to the interaction of SC stray fields, associated to supercurrent loops, with the non-trivial 3D remanent magnetic structure of FM nano-rods. This work unravels the importance of addressing quantitatively the effect of stray magnetic fields from both, the superconductor and the ferromagnet in hybrid magnetic nano-devices based on high temperature superconductors.
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