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Datt G, Kotnana G, Maddu R, Vallin Ö, Joshi DC, Peddis D, Barucca G, Kamalakar MV, Sarkar T. Combined Bottom-Up and Top-Down Approach for Highly Ordered One-Dimensional Composite Nanostructures for Spin Insulatronics. ACS Appl Mater Interfaces 2021; 13:37500-37509. [PMID: 34325507 PMCID: PMC8397244 DOI: 10.1021/acsami.1c09582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Engineering magnetic proximity effects-based devices requires developing efficient magnetic insulators. In particular, insulators, where magnetic phases show dramatic changes in texture on the nanometric level, could allow us to tune the proximity-induced exchange splitting at such distances. In this paper, we report the fabrication and characterization of highly ordered two-dimensional arrays of LaFeO3 (LFO)-CoFe2O4 (CFO) biphasic magnetic nanowires, grown on silicon substrates using a unique combination of bottom-up and top-down synthesis approaches. The regularity of the patterns was confirmed using atomic force microscopy and scanning electron microscopy techniques, whereas magnetic force microscopy images established the magnetic homogeneity of the patterned nanowires and absence of any magnetic debris between the wires. Transmission electron microscopy shows a close spatial correlation between the LFO and CFO phases, indicating strong grain-to-grain interfacial coupling, intrinsically different from the usual core-shell structures. Magnetic hysteresis loops reveal the ferrimagnetic nature of the composites up to room temperature and the presence of a strong magnetic coupling between the two phases, and electrical transport measurements demonstrate the strong insulating behavior of the LFO-CFO composite, which is found to be governed by Mott-variable range hopping conduction mechanisms. A shift in the Raman modes in the composite sample compared to those of pure CFO suggests the existence of strain-mediated elastic coupling between the two phases in the composite sample. Our work offers ordered composite nanowires with strong interfacial coupling between the two phases that can be directly integrated for developing multiphase spin insulatronic devices and emergent magnetic interfaces.
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Affiliation(s)
- Gopal Datt
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, Uppsala SE-751
03, Sweden
| | - Ganesh Kotnana
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, Uppsala SE-751
03, Sweden
| | - Ramu Maddu
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, Uppsala SE-751
03, Sweden
| | - Örjan Vallin
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, Uppsala SE-751
03, Sweden
| | - Deep Chandra Joshi
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, Uppsala SE-751
03, Sweden
| | - Davide Peddis
- Dipartimento
di Chimica e Chimica Industriale, Università
di Genova, Via Dodecaneso
31, Genova I-16146, Italy
- Institute
of Structure of Matter, Italian National
Research Council (CNR), Monterotondo
Scalo, 00015 Rome, Italy
| | - Gianni Barucca
- Department
SIMAU, Università Politecnica delle
Marche, Via Brecce Bianche
12, Ancona 60131, Italy
| | - M. Venkata Kamalakar
- Department
of Physics and Astronomy, Uppsala University, Uppsala SE-751 20, Sweden
| | - Tapati Sarkar
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, Uppsala SE-751
03, Sweden
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Muscas G, Jönsson PE, Serrano IG, Vallin Ö, Kamalakar MV. Ultralow magnetostrictive flexible ferromagnetic nanowires. Nanoscale 2021; 13:6043-6052. [PMID: 33885602 DOI: 10.1039/d0nr08355k] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The integration of magneto-electric and spintronic sensors to flexible electronics presents a huge potential for advancing flexible and wearable technologies. Magnetic nanowires are core components for building such devices. Therefore, realizing flexible magnetic nanowires with engineered magneto-elastic properties is key to flexible spintronic circuits, as well as creating unique pathways to explore complex flexible spintronic, magnonic, and magneto-plasmonic devices. Here, we demonstrate highly resilient flexible ferromagnetic nanowires on transparent flexible substrates for the first time. Through extensive magneto-optical Kerr experiments, exploring the Villari effect, we reveal an ultralow magnetostrictive constant in nanowires, a two-order reduced value compared to bulk values. In addition, the flexible magnetic nanowires exhibit remarkable resilience sustaining bending radii ∼5 mm, high endurance, and enhanced elastic limit compared to thin films of similar thickness and composition. The observed performance is corroborated by our micro-magnetic simulations and can be attributed to the reduced size and strong nanostructure-interfacial effects. Such stable magnetic nanowires with ultralow magnetostriction open up new opportunities for stable surface mountable and wearable spintronic sensors, advanced nanospintronic circuits, and for exploring novel strain-induced quantum effects in hybrid devices.
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Affiliation(s)
- Giuseppe Muscas
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
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Abstract
Owing to their unprecedented electronic properties, graphene and two-dimensional (2D) crystals have brought fresh opportunities for advances in planar spintronic devices. Graphene is an ideal medium for spin transport while being an exceptionally resilient material for flexible nanoelectronics. However, these extraordinary traits have never been combined to create flexible graphene spin circuits. Realizing such circuits could lead to bendable strain-spin sensors, as well as a unique platform to explore pure spin current based operations and low-power 2D flexible nanoelectronics. Here, we demonstrate graphene spin circuits on flexible substrates for the first time. Despite the rough topography of the flexible substrates, these circuits prepared with chemical vapor deposited monolayer graphene reveal an efficient room temperature spin transport with distinctively large spin diffusion coefficients ∼0.2 m2 s-1. Compared to earlier graphene devices on Si/SiO2 substrates, such values are up to 20 times larger, leading to one order higher spin signals and an enhanced spin diffusion length ∼10 μm in graphene-based nonlocal spin valves fabricated using industry standard systems. This high performance arising out of a characteristic substrate terrain shows promise of a scalable and flexible platform towards flexible 2D spintronics. Our innovation is a key step for the exploration of strain-dependent 2D spin phenomena and paves the way for flexible graphene spin memory-logic units and planar spin sensors.
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Affiliation(s)
- I G Serrano
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - J Panda
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - Fernand Denoel
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - Örjan Vallin
- Department of Engineering Sciences , Uppsala University , Box 534, SE 751 21 , Uppsala , Sweden
| | - Dibya Phuyal
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - Olof Karis
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - M Venkata Kamalakar
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
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