Radiation Studies of Spin-Transfer Torque Materials and Devices

Hughes, H.L.; Bussmann, K.; McMarr, P.J.; Cheng, Shuo; Shull, Robert D.; Chen, A. P.; Schäfer, Sebastian; Mewes, Tim; Ong, A.; Chen, E.; Mendenhall, Marcus H.; Reed, Robert A.

doi:10.1109/tns.2012.2223487

Cited by 43 publications

(32 citation statements)

References 9 publications

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“…7 and 8, this dependence of the R 0 degradation on the number of received ions suggests that the observed degradation is caused by the ion bombardments. A similar dose effect is also detected in the previous heavy ion and proton studies [6], [8]. They indicate possible changes in the ferromagnetic layers such as defect (displacement) generations and magnetic domain changes while the mechanism has not yet been throughly explained.…”

Section: Resultssupporting

confidence: 82%

“…This differentiates our study from the previous ones [6]- [8] (see again Table I) as well as [4], in which an MRAM chip was fed from a power supply during irradiation, but the voltage bias applied to MTJ elements is expected to be zero, in principle, because the chip operated in the data retention mode. Note that the bias voltages applied during irradiation in this study are enough small to keep the programmed magnetization.…”

Section: B Irradiationmentioning

confidence: 83%

“…Fabricated in the most advanced CoFeB-MgO MTJ technology [5], a p-MTJ stack with a diameter of 70 nm is investigated mainly from the view point of single-event upset (SEU) tolerance. As shown in Table I, radiation effects given by gamma, protons, and neutrons are reported elsewhere [7], [8]. Heavy ion effects are reported in [6], which has studied an AlO x -based MTJ associated with the external magnetic-field switching.…”

Section: Introductionmentioning

confidence: 99%

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Influence of heavy ion irradiation on perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions

Kobayashi¹,

Kakehashi²,

Hirose³

et al. 2013

2013 14th European Conference on Radiation and Its Effects on Components and Systems (RADECS)

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A non-volatile memory element that is called a perpendicular-anisotropy magnetic tunnel junction has been fabricated in a CoFeB/MgO/CoFeB film stack technology. It exhibits two stable resistance values, high or low, depending on the relative direction of magnetization of the two ferromagnetic CoFeB layers. After programmed into the high resistance state with a current injection scheme based on the spin transfer torque theory, the tunnel junction has been exposed to 15-MeV Si ions in different voltage stress conditions. It has been observed that the tested structure remains in the programmed high resistance state after received the bombardments of several tens of Si ions and more, even under the stressed situations. A time-domain analysis has proven that this result is due to the perfect immunity of the tested magnetic tunnel junction to single event upsets. A resistance degradation due to the heavy-ion irradiation has been detected through a precise parameter analysis based on a tunneling theory but negligibly small, 1%.

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Section: Resultssupporting

confidence: 82%

Section: B Irradiationmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Influence of heavy ion irradiation on perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions

Kobayashi¹,

Kakehashi²,

Hirose³

et al. 2013

2013 14th European Conference on Radiation and Its Effects on Components and Systems (RADECS)

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“…This switching scheme makes it possible for MTJs to have a small feature size but raises a question about their radiation tolerance: It is unclear whether this direct-current-controlled device can withstand the flood of electrons and holes produced by radiation. In this regard, an STT MTJ was tested by protons [7], but not yet heavy ions. This paper reports the results of an experiment on heavy ion (15-MeV Si) irradiation of p-MTJs with STT switching.…”

Section: Influence Of Heavy Ion Irradiation On I Introductionmentioning

confidence: 99%

“…A p-MTJ stack with a diameter of 70 nm was fabricated using the most advanced CoFeB-MgO MTJ technology [8] and investigated mainly from the viewpoint of its single-event upset (SEU) tolerance. Table I lists the relevant radiation effects of gamma rays, protons, and neutrons [5], [7]. In particular, heavy ion effects were reported in a study on an -based MTJ with external magnetic-field switching [6].…”

Section: Influence Of Heavy Ion Irradiation On I Introductionmentioning

confidence: 99%

Influence of Heavy Ion Irradiation on Perpendicular-Anisotropy CoFeB-MgO Magnetic Tunnel Junctions

Kobayashi

Kakehashi

Hirose

et al. 2014

IEEE Trans. Nucl. Sci.

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A non-volatile memory element called a perpendicular-anisotropy magnetic tunnel junction was fabricated using CoFeB/MgO/CoFeB film stack technology. It exhibits two stable resistance values, high or low, depending on the relative directions of the magnetizations of the two ferromagnetic CoFeB layers. After being programmed into the high resistance state with a current injection scheme based on the spin transfer torque theory, the tunnel junction was exposed to 15-MeV Si ions under different voltage stress conditions. The tested structure remained in the programmed high resistance state after being bombarded with 10-100 Si ions, even under the stressed situations. A time-domain analysis proved that this result is due to the perfect immunity of the tested magnetic tunnel junction to single event upsets. Some degradation in resistance due to the heavy-ion irradiation was detected through a precise parameter analysis based on a tunneling theory but it was negligibly small (1%). There were no statistically significant changes in the thermal stability factor before and after irradiation, and this means the long-term retention properties remained unchanged.

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A Coupled Spintronics Neuromorphic Approach for High‐Performance Reservoir Computing

Akashi

Kuniyoshi

Tsunegi

et al. 2022

Advanced Intelligent Systems

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The rapid development in the field of artificial intelligence has increased the demand for neuromorphic computing hardware and its information‐processing capability. A spintronics device is a promising candidate for neuromorphic computing hardware and can be used in extreme environments due to its high resistance to radiation. Improving the information‐processing capability of neuromorphic computing is an important challenge for implementation. Herein, a novel neuromorphic computing framework using spintronics devices is proposed. This framework is called coupled spintronics reservoir (CSR) computing and exploits the high‐dimensional dynamics of coupled spin‐torque oscillators as a computational resource. The relationships among various bifurcations of the CSR and its information‐processing capabilities through numerical experiments are analyzed and it is found that certain configurations of the CSR boost the information‐processing capability of the spintronics reservoir toward or even beyond the standard level of machine learning networks. The effectiveness of our approach is demonstrated through conventional machine learning benchmarks and edge computing in real physical experiments using pneumatic artificial muscle‐based wearables, which assist human operations in various environments. This study significantly advances the availability of neuromorphic computing for practical uses.

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Radiation Studies of Spin-Transfer Torque Materials and Devices

Cited by 43 publications

References 9 publications

Influence of heavy ion irradiation on perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions

Influence of heavy ion irradiation on perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions

Influence of Heavy Ion Irradiation on Perpendicular-Anisotropy CoFeB-MgO Magnetic Tunnel Junctions

A Coupled Spintronics Neuromorphic Approach for High‐Performance Reservoir Computing

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