Impact of boron diffusion at MgO grain boundaries on magneto-transport properties of MgO/CoFeB/W magnetic tunnel junctions

Xu, Xiandong; Mukaiyama, Koki; Kasai, S.; Ohkubo, T.; Hono, K.

doi:10.1016/j.actamat.2018.09.028

Cited by 29 publications

(19 citation statements)

References 44 publications

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“…Nanobeam electron diffraction patterns were taken with a 10-µm-diamter condenser aperture. Element-selected analysis were carried out via energy-dispersive X-ray spectroscopy (EDS) [61]. to Bi which is practically immiscible with any of these elements.…”

Section: S1 Stem Results Of Filmsmentioning

confidence: 99%

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The spin Hall effect of Bi-Sb alloys driven by thermally excited Dirac-like electrons

Chi

Lau

et al. 2020

Sci. Adv.

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We have studied the charge to spin conversion in Bi 1−x Sb x /CoFeB heterostructures. The spin Hall conductivity (SHC) of the sputter deposited heterostructures exhibits a high plateau at Bi-rich compositions, corresponding to the topological insulator phase, followed by a decrease of SHC for Sb-richer alloys, in agreement with the calculated intrinsic spin Hall effect of Bi 1−x Sb x alloy. The SHC increases with increasing thickness of the Bi 1−x Sb x alloy before it saturates, indicating that it is the bulk of the alloy that predominantly contributes to the generation of spin current; the topological surface states, if present in the films, play little role. Surprisingly, the SHC is found to increase with increasing temperature, following the trend of carrier density. These results suggest that the large SHC at room temperature, with a spin Hall efficiency exceeding 1 and an extremely large spin current mobility, is due to increased number of Dirac-like, thermally-excited electrons in the L valley of the narrow gap Bi 1−x Sb x alloy.

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Section: S1 Stem Results Of Filmsmentioning

confidence: 99%

“…SOT measurements of a standard sample: Pt/CoFeB.References[61][62][63][64][65][66][67][68][69][70].Acknowledgements: We thank Y. Fuseya, H. Kohno, G. Qu for helpful discussions.…”

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confidence: 99%

The spin Hall effect of Bi-Sb alloys driven by thermally excited Dirac-like electrons

Chi

Lau

et al. 2020

Sci. Adv.

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“…To obtain high thermal tolerance, one needs to control diffusion of boron from CoFeB to the adjacent layer because boron concentration plays a crucial role in realizing perpendicular easy axis [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. As shown in Figure 2a,c, all the s-MTJs showed an increase of TMR ratio up to a specific temperature, above which the TMR ratio degraded.…”

Section: (1) High Thermal Tolerance By Controlling Boron Composition mentioning

confidence: 99%

A Recent Progress of Spintronics Devices for Integrated Circuit Applications

Endoh

Honjo

2018

JLPEA

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Nonvolatile (NV) memory is a key element for future high-performance and low-power microelectronics. Among the proposed NV memories, spintronics-based ones are particularly attractive for applications, owing to their low-voltage and high-speed operation capability in addition to their high-endurance feature. There are three types of spintronics devices with different writing schemes: spin-transfer torque (STT), spin-orbit torque (SOT), and electric field (E-field) effect on magnetic anisotropy. The NV memories using STT have been studied and developed most actively and are about to enter into the market by major semiconductor foundry companies. On the other hand, a development of the NV memories using other writing schemes are now underway. In this review article, first, the recent advancement of the spintronics device using STT and the NV memories using them are reviewed. Next, spintronics devices using the other two writing schemes (SOT and E-field) are briefly reviewed, including issues to be addressed for the NV memories application.

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“…Yet, the role of boron composition in damping has largely been overlooked since the extrinsic damping contributions particularly spin‐pumping from the adjacent heavy metal, which also serves as a boron sink, [ 10,22,23 ] largely determines the effective damping. However, the double MgO design leaves an open question on the impact of boron where spin pumping contributions are minimized.…”

Section: Introductionmentioning

confidence: 99%

Tuning Damping and Magnetic Anisotropy in Ultrathin Boron‐Engineered MgO/Co–Fe–B/MgO Heterostructures

Lourembam

Khoo²,

Qiu

et al. 2021

Adv Elect Materials

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Nanometer‐thick Co–Fe–B/MgO based structures have been widely accepted as the preferred system for immediate and long‐term goals in magnetic random access memory (MRAM) devices because of excellent spin‐torque efficiency and promise for high‐density MRAM. To realize next‐generation ultra‐low‐power MRAM, further lowering of power consumption in these structures is a crucial ongoing effort. Gilbert damping is one critical material parameter toward lowering energy consumption but is traditionally large (≈10−2) in these Co–Fe–B/MgO systems. Here, Gilbert damping of (1.3 ± 0.3) × 10−3 from a perpendicular double Co–Fe–B/MgO interface system engineered at different boron compositions is reported. Remarkably, this value is achieved with ≈1 nm of Co–Fe–B thickness while maintaining magnetic anisotropy of 0.4 Merg cc−1. An unusual damping trend that scales with layer thickness in high‐boron content films established from both experiments and first‐principles calculations is reported.

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Impact of boron diffusion at MgO grain boundaries on magneto-transport properties of MgO/CoFeB/W magnetic tunnel junctions

Cited by 29 publications

References 44 publications

The spin Hall effect of Bi-Sb alloys driven by thermally excited Dirac-like electrons

The spin Hall effect of Bi-Sb alloys driven by thermally excited Dirac-like electrons

A Recent Progress of Spintronics Devices for Integrated Circuit Applications

Tuning Damping and Magnetic Anisotropy in Ultrathin Boron‐Engineered MgO/Co–Fe–B/MgO Heterostructures

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