Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability
Magnetic coupling between two CoFeB layers through the W insertion layer is important in the conventional double CoFeB/MgO interface, magnetic tunneling junctions (MTJs) (double-MTJs) with MgO/CoFeB/W/CoFeB/MgO free layer stack because it increases the effective magnetic volume of the free layer. Th...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2021-02-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/9.0000048 |
| _version_ | 1818672062161485824 |
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| author | K. Nishioka H. Honjo H. Naganuma T. V. A. Nguyen M. Yasuhira S. Ikeda T. Endoh |
| author_facet | K. Nishioka H. Honjo H. Naganuma T. V. A. Nguyen M. Yasuhira S. Ikeda T. Endoh |
| author_sort | K. Nishioka |
| collection | DOAJ |
| description | Magnetic coupling between two CoFeB layers through the W insertion layer is important in the conventional double CoFeB/MgO interface, magnetic tunneling junctions (MTJs) (double-MTJs) with MgO/CoFeB/W/CoFeB/MgO free layer stack because it increases the effective magnetic volume of the free layer. The magnetic coupling energy constant per unit area, Jcpl, between two CoFeB layers through the W layer and the effective perpendicular magnetic anisotropy (PMA) energy constant per unit area, Kefft*, were investigated for conventional double-MTJs with various W insertion layer thicknesses. As the W layer thickness increased, Kefft* increased and Jcpl decreased. There exists a trade-off relationship between Jcpl and Kefft*. In conventional double-MTJs with a single W insertion layer, large values for Jcpl and Kefft* were difficult to obtain simultaneously. To improve this tradeoff, we employed a free layer stack with a thin ferromagnetic layer (ferromagnetic bridge layer: FBL) located in the W insertion layer. In the double-MTJs with FBL annealed at 400 °C, a large Jcpl value of 0.37 mJ/m2 was achieved while maintaining the maximum values of Kefft*. Accordingly, the MTJ with FBL provides an MTJ stack structure for obtaining high thermal stability. |
| first_indexed | 2024-12-17T07:33:55Z |
| format | Article |
| id | doaj.art-eb9ad07a83b8417b968f252dd0b545ec |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-12-17T07:33:55Z |
| publishDate | 2021-02-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-eb9ad07a83b8417b968f252dd0b545ec2022-12-21T21:58:25ZengAIP Publishing LLCAIP Advances2158-32262021-02-01112025231025231-510.1063/9.0000048Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stabilityK. Nishioka0H. Honjo1H. Naganuma2T. V. A. Nguyen3M. Yasuhira4S. Ikeda5T. Endoh6Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanCenter for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanCenter for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanCenter for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanCenter for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanCenter for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanCenter for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-8572, JapanMagnetic coupling between two CoFeB layers through the W insertion layer is important in the conventional double CoFeB/MgO interface, magnetic tunneling junctions (MTJs) (double-MTJs) with MgO/CoFeB/W/CoFeB/MgO free layer stack because it increases the effective magnetic volume of the free layer. The magnetic coupling energy constant per unit area, Jcpl, between two CoFeB layers through the W layer and the effective perpendicular magnetic anisotropy (PMA) energy constant per unit area, Kefft*, were investigated for conventional double-MTJs with various W insertion layer thicknesses. As the W layer thickness increased, Kefft* increased and Jcpl decreased. There exists a trade-off relationship between Jcpl and Kefft*. In conventional double-MTJs with a single W insertion layer, large values for Jcpl and Kefft* were difficult to obtain simultaneously. To improve this tradeoff, we employed a free layer stack with a thin ferromagnetic layer (ferromagnetic bridge layer: FBL) located in the W insertion layer. In the double-MTJs with FBL annealed at 400 °C, a large Jcpl value of 0.37 mJ/m2 was achieved while maintaining the maximum values of Kefft*. Accordingly, the MTJ with FBL provides an MTJ stack structure for obtaining high thermal stability.http://dx.doi.org/10.1063/9.0000048 |
| spellingShingle | K. Nishioka H. Honjo H. Naganuma T. V. A. Nguyen M. Yasuhira S. Ikeda T. Endoh Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability AIP Advances |
| title | Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability |
| title_full | Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability |
| title_fullStr | Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability |
| title_full_unstemmed | Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability |
| title_short | Enhancement of magnetic coupling and magnetic anisotropy in MTJs with multiple CoFeB/MgO interfaces for high thermal stability |
| title_sort | enhancement of magnetic coupling and magnetic anisotropy in mtjs with multiple cofeb mgo interfaces for high thermal stability |
| url | http://dx.doi.org/10.1063/9.0000048 |
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