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Girardi D, Finizio S, Donnelly C, Rubini G, Mayr S, Levati V, Cuccurullo S, Maspero F, Raabe J, Petti D, Albisetti E. Three-dimensional spin-wave dynamics, localization and interference in a synthetic antiferromagnet. Nat Commun 2024; 15:3057. [PMID: 38594233 PMCID: PMC11004151 DOI: 10.1038/s41467-024-47339-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 03/28/2024] [Indexed: 04/11/2024] Open
Abstract
Spin waves are collective perturbations in the orientation of the magnetic moments in magnetically ordered materials. Their rich phenomenology is intrinsically three-dimensional; however, the three-dimensional imaging of spin waves has so far not been possible. Here, we image the three-dimensional dynamics of spin waves excited in a synthetic antiferromagnet, with nanoscale spatial resolution and sub-ns temporal resolution, using time-resolved magnetic laminography. In this way, we map the distribution of the spin-wave modes throughout the volume of the structure, revealing unexpected depth-dependent profiles originating from the interlayer dipolar interaction. We experimentally demonstrate the existence of complex three-dimensional interference patterns and analyze them via micromagnetic modelling. We find that these patterns are generated by the superposition of spin waves with non-uniform amplitude profiles, and that their features can be controlled by tuning the composition and structure of the magnetic system. Our results open unforeseen possibilities for the study and manipulation of complex spin-wave modes within nanostructures and magnonic devices.
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Affiliation(s)
- Davide Girardi
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Simone Finizio
- Swiss Light Source, Paul Scherrer Institut; Forschungsstrasse 111 5232 PSI, Villigen, Switzerland
| | - Claire Donnelly
- Max Planck Institute for Chemical Physics of Solids; Nöthnitzer Str. 40, 01187, Dresden, Germany
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, Hiroshima, 739-8526, Japan
| | - Guglielmo Rubini
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Sina Mayr
- Swiss Light Source, Paul Scherrer Institut; Forschungsstrasse 111 5232 PSI, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | - Valerio Levati
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Simone Cuccurullo
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Federico Maspero
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Jörg Raabe
- Swiss Light Source, Paul Scherrer Institut; Forschungsstrasse 111 5232 PSI, Villigen, Switzerland
| | - Daniela Petti
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy.
| | - Edoardo Albisetti
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy.
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Kisała J, Kociubiński A, Jartych E. Influence of the NiFe/Cu/NiFe Structure Dimensions and Position in External Magnetic Field on Resistance Changes under the Magnetoresistance Effect. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4810. [PMID: 37445124 DOI: 10.3390/ma16134810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023]
Abstract
The subject of this work is NiFe/Cu/NiFe thin-film structures made by magnetron sputtering and showing the phenomenon of magnetoresistance. Three series of samples differing in spatial dimensions and thickness of the Cu spacer were produced. During the sputtering process, an external magnetic field of approx. 10 mT was applied to the substrate. Measurements of the resistance of the structures were carried out in the field of neodymium magnets in three different positions of the sample in relation to the direction of the field. The measurements allowed us to indicate in which position the structures of different series achieved the greatest changes in resistance. For each of the three series of layer systems, the nature of changes in the determined coefficient of giant magnetoresistance ΔR/R remained similar, while for the series with the smallest copper thickness (2.5 nm), the coefficient reached the highest value of about 2.7‱. In addition, impedance measurements were made for the structures of each series in the frequency range from 100 Hz to 100 kHz. For series with a thinner copper layer, a decrease in impedance values was observed in the 10-100 kHz range.
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Affiliation(s)
- Jakub Kisała
- Department of Electronics and Information Technology, Faculty of Electrical Engineering and Computer Science, Lublin University of Technology, 20-618 Lublin, Poland
| | - Andrzej Kociubiński
- Department of Electronics and Information Technology, Faculty of Electrical Engineering and Computer Science, Lublin University of Technology, 20-618 Lublin, Poland
| | - Elżbieta Jartych
- Department of Electronics and Information Technology, Faculty of Electrical Engineering and Computer Science, Lublin University of Technology, 20-618 Lublin, Poland
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Yan S, Chen W, Zhou Z, Li Z, Cao Z, Lu S, Zhu D, Zhao W, Leng Q. Reversal of the Pinning Direction in the Synthetic Spin Valve with a NiFeCr Seed Layer. NANOMATERIALS 2022; 12:nano12122077. [PMID: 35745414 PMCID: PMC9230223 DOI: 10.3390/nano12122077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 06/11/2022] [Accepted: 06/13/2022] [Indexed: 12/04/2022]
Abstract
The effect of the seed layers on the magnetic properties of the giant magnetoresistance thin films has received a lot of attention. Here, a synthetic spin valve film stack with a wedge-shaped NiFeCr seed layer is deposited and annealed following a zero-field cooling procedure. The film crystallinity and magnetic properties are studied as a function of the NiFeCr seed layer thickness. It is found that the exchange coupling field from the IrMn/CoFe interface and the antiferromagnetic coupling field in the synthetic antiferromagnet both increase as the seed layer thickness increases, indicating the perfection of film texture. In this film, the critical thickness of the NiFeCr seed layer for the formation of the ordered IrMn3 texture is about 9.3 nm. Meanwhile, a reversal of the pinning direction in the film is observed at this critical thickness of NiFeCr. This phenomenon can be explained in a free energy model by the competition effect between the exchange coupling and the interlayer coupling during the annealing process.
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Affiliation(s)
- Shaohua Yan
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
| | - Weibin Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China;
| | - Zitong Zhou
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
| | - Zhi Li
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
| | - Zhiqiang Cao
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
| | - Shiyang Lu
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
| | - Dapeng Zhu
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
| | - Weisheng Zhao
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
- Correspondence: (W.Z.); (Q.L.); Tel.: +86-532-5866-6763 (W.Z. & Q.L.)
| | - Qunwen Leng
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China; (S.Y.); (Z.Z.); (Z.L.); (Z.C.); (D.Z.)
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266100, China;
- Correspondence: (W.Z.); (Q.L.); Tel.: +86-532-5866-6763 (W.Z. & Q.L.)
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Abstract
In this study, the addition of Y to CoFeB alloy can refine the grain size to study the magnetic, adhesion and optical properties of as-deposited and annealed CoFeB alloy. XRD analysis shows that CoFeB(110) has a BCC CoFeB (110) nanocrystalline structure with a thickness of 10–50 nm under four heat-treatment conditions, and a CoFeB(110) peak at 44° (2θ). The measurements of saturation magnetization (MS) and low frequency alternate-current magnetic susceptibility (χac) revealed a thickness effect owed to exchange coupling. The maximum MS of the 300 °C annealed CoFeBY film with a thickness of 50 nm was 925 emu/cm3 (9.25 × 105 A/m). The maximum χac value of the 300 °C annealed CoFeBY nanofilms with a thickness of 50 nm was 0.165 at 50 Hz. After annealing at 300 °C, CoFeBY nanofilms exhibited the highest surface energy of 31.07 mJ/mm2, where the thickness of the nanofilms was 40 nm. Compared with the as-deposited CoFeBY nanofilms, due to the smaller average grain size after annealing, the transmittance of the annealed nanofilms increased. Importantly, when a CoFeB seed or buffer layer was replaced by a CoFeBY nanofilm, the thermal stability of the CoFeBY nanofilms was improved, promoting themselves on the practical MTJ applications.
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Tian F, Zhang Y, Zhou C, Zhao Q, Yu Z, Murtaza A, Zuo W, Yang S, Song X. Giant Vertical Magnetization Shift Caused by Field-Induced Ferromagnetic Spin Reconfiguration in Ni 50Mn 36Ga 14 Alloy. MATERIALS 2020; 13:ma13214701. [PMID: 33105593 PMCID: PMC7659958 DOI: 10.3390/ma13214701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 11/16/2022]
Abstract
Vertical magnetization shift (VMS) is a special type of exchange bias effect that may lead to a revolution in future ultrahigh-density magnetic recording technology. However, there are very few reports focusing on the performance of VMS due to the unclear mechanism. In this paper, a giant vertical magnetization shift (ME) of 6.34 emu/g is reported in the Ni50Mn36Ga14 alloy. The VMS can be attributed to small ferromagnetic ordered regions formed by spin reconfiguration after field cooling, which are embedded in an antiferromagnetic matrix. The strong cooling-field dependence, temperature dependence, and training effect all corroborate the presence of spin reconfiguration and its role in the VMS. This work can enrich VMS research and increase its potential in practical applications as well.
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