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Tang H, Mamakhel MAH, Christensen M. High coercivity SmCo 5 synthesized with assistance of colloidal SiO 2. Sci Rep 2021; 11:4682. [PMID: 33633181 PMCID: PMC7907374 DOI: 10.1038/s41598-021-83826-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 02/08/2021] [Indexed: 11/09/2022] Open
Abstract
SmCo5 is one of the most promising candidates for achieving a hard magnet with a high coercivity. Usually, composition, morphology, and size determine the coercivity of a magnet, however, it is challenging to synthesize phase pure SmCo5 with optimal size and high coercivity. In this paper, we report on the successful synthesis of phase pure SmCo5 with spherical/prolate spheroids shape. Size control is obtained by utilizing colloidal SiO2 as a template preventing aggregation and growth of the precursor. The amount of SiO2 nanoparticles (NPs) in the precursor tunes the average particle size (APS) of the synthesized SmCo5 with particle dimension from 740 to 504 nm. As-prepared pure SmCo5 fine powder obtained from using 2 ml SiO2 suspension possesses an APS of 625 nm and exhibits an excellent coercivity of 2986 kA m-1 (37.5 kOe) without alignment of the particles prior to magnetisation measurements. Comparing with a reference sample prepared without adding any SiO2 NPs, an enhancement of 35% of the coercivity was achieved. The improvement is due to phase purity, stable single-domain (SSD) size, and shape anisotropy originating from the prolate spheroid particles.
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Affiliation(s)
- Hao Tang
- Center for Materials Crystallography (CMC), Department of Chemistry, Aarhus University, 8000, Aarhus, Denmark.,Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000, Aarhus, Denmark
| | | | - Mogens Christensen
- Center for Materials Crystallography (CMC), Department of Chemistry, Aarhus University, 8000, Aarhus, Denmark. .,Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000, Aarhus, Denmark.
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Cirillo C, Barone C, Bradshaw H, Urban F, Di Bernardo A, Mauro C, Robinson JWA, Pagano S, Attanasio C. Magnetotransport and magnetic properties of amorphous [Formula: see text] thin films. Sci Rep 2020; 10:13693. [PMID: 32792527 PMCID: PMC7426968 DOI: 10.1038/s41598-020-70646-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/23/2020] [Indexed: 11/08/2022] Open
Abstract
[Formula: see text] is an intermetallic compound with a bulk Curie temperature ([Formula: see text]) of 6-13 K. While existing studies have focused on [Formula: see text] crystals, amorphous thin-films of [Formula: see text] are potentially important since they would be magnetically soft without magnetocrystalline anisotropy, meaning that small external magnetic fields could reverse the direction of their magnetization. Here, we report [Formula: see text] thin-films with a thickness in the 5-200 nm range, deposited by DC magnetron sputtering onto Si(100). Films are amorphous with a weak temperature-dependent resistivity with values ranging between 150 and 300 [Formula: see text] cm. By means of noise spectroscopy, by analyzing the time-dependence of fluctuation-induced voltages, it is found that at low temperatures the resistance fluctuations are due to the Kondo effect. Volume magnetometry indicates [Formula: see text] K with a magnetic coercive field of 30 mT at 5 K for a 125-nm-thick film. The results are promising for the development of Ferromagnet(F)/Superconductor(S)/Ferromagnet(F) pseudo spin-valve devices based on amorphous [Formula: see text] thin films.
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Affiliation(s)
- Carla Cirillo
- CNR-SPIN, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, 84084 Fisciano, SA Italy
| | - Carlo Barone
- CNR-SPIN, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- INFN Gruppo Collegato di Salerno, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
| | - Harry Bradshaw
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS UK
| | - Francesca Urban
- CNR-SPIN, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- INFN Gruppo Collegato di Salerno, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
| | - Angelo Di Bernardo
- Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - Costantino Mauro
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, 84084 Fisciano, SA Italy
| | - Jason W. A. Robinson
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS UK
| | - Sergio Pagano
- CNR-SPIN, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- INFN Gruppo Collegato di Salerno, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
| | - Carmine Attanasio
- CNR-SPIN, c/o Università degli Studi di Salerno, 84084 Fisciano, SA Italy
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, 84084 Fisciano, SA Italy
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