Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions

Watanabe, K.; Jinnai, Butsurin; Fukami, Shunsuke; Sato, Hideo; Ohno, Hideo

doi:10.1038/s41467-018-03003-7

Cited by 167 publications

(113 citation statements)

References 43 publications

(53 reference statements)

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“…Overall, MgO spintronics represents a compelling route. Indeed, it benefits from both industrial penetration 54,61 and knowledge on how oxygen vacancies craft the spintronic nanotransport path [21][22][23][24]53 , boasts lateral sizes down to 4.3 nm 62 , and has been conjugated with half-metallic electrodes operating at RT 17 . PM centers can be formed in MgO by trapping C, N or Si on oxygen vacancies (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Spin-driven electrical power generation at room temperature

et al. 2019

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Ongoing research is exploring novel energy concepts ranging from classical to quantum thermodynamics. Ferromagnets carry substantial built-in energy due to ordered electron spins. Here, we propose to generate electrical power at room temperature by utilizing this magnetic energy to harvest thermal fluctuations on paramagnetic centers using spintronics. Our spin engine rectifies current fluctuations across the paramagnetic centers' spin states by utilizing so-called 'spinterfaces' with high spin polarization. Analytical and ab-initio theories suggest that experimental data at room temperature from a single MgO magnetic tunnel junction (MTJ) be linked to this spin engine. Device downscaling, other spintronic solutions to select a transport spin channel, and dual oxide/organic materials tracks to introduce paramagnetic centers into the tunnel barrier, widen opportunities for routine device reproduction. At present MgO MTJ densities in next-generation memories, this spin engine could lead to 'always-on' areal power densities that are highly competitive relative to other energy harvesting strategies.

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Section: Discussionmentioning

confidence: 99%

Spin-driven electrical power generation at room temperature

et al. 2019

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“…random access memory (MRAM) with large perpendicular magnetic anisotropy is attractive for its good scalability and high thermal stability [4,5] during fast sub-nanosecond write, [6] the required high write current density can exert severe stress on the magnetic tunnel junction (MTJ) and induce wear-out and breakdown of the MTJ barrier, [7] leading ultimately to degradation of the memory cell. Meanwhile, the shared read/write path can lead to write upon read errors.…”

Section: Energy-efficient Ultrafast Sot-mrams Based Onmentioning

confidence: 99%

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au_0.25Pt_0.75

Zhu

Shi

et al. 2020

Adv Elect Materials

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As shown in Figure 1b-d, the SOT-MTJ devices were lithographically patterned from sputter-deposited multilayer stacks consisting of Si/SiO 2 /Ta 1/Au 0.25 Pt 0.75 5/Hf 0.5/ Fe 0.6 Co 0.2 B 0.2Many key electronic technologies (e.g., large-scale computing, machine learning, and superconducting electronics) require new memories that are at the same time fast, reliable, energy-efficient, and of low-impedance, which has remained a challenge. Nonvolatile magnetoresistive random access memories (MRAMs) driven by spin-orbit torques (SOTs) have promise to be faster and more energy-efficient than conventional semiconductor and spin-transfer-torque magnetic memories. It is reported that the spin Hall effect of low-resistivity Au 0.25 Pt 0.75 thin films enables ultrafast antidamping-torque switching of SOT-MRAM devices for current pulse widths as short as 200 ps. If combined with industrial-quality lithography and already-demonstrated interfacial engineering, an optimized MRAM cell based on Au 0.25 Pt 0.75 can have energy-efficient, ultrafast, and reliable switching, for example, a write energy of <1 fJ (<50 fJ) for write error rate of 50% (<10 −5 ) for 1 ns pulses. The antidamping torque switching of the Au 0.25 Pt 0.75 devices is ten times faster than expected from a rigid macrospin model, most likely because of the fast micromagnetics due to the enhanced nonuniformity within the free layer. The feasibility of Au 0.25 Pt 0.75 -based SOT-MRAMs as a candidate for ultrafast, reliable, energy-efficient, low-impedance, and unlimited-endurance memory is demonstrated.

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“…As expected, read disturbance increases with read voltage and temperature. Thicker free layer thickness also increases read disturbance because of the reduced perpendicular magnetic anisotropy and hence thermal stability [44]. Fortunately, MeRAM is free from read disturbance because its read current direction is opposite to the direction that can switch the MTJ.…”

Section: Write Error and Read Disturbance Rate Under Variationmentioning

confidence: 99%

Adaptive MRAM Write and Read with MTJ Variation Monitor

Wang

Lee

Grèzes

et al. 2021

IEEE Trans. Emerg. Topics Comput.

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Temperature and wafer-level process variations significantly degrade operation efficiency of Spin-transfer torque random access memory (STT-MRAM) and magnetoelectric random access memory (MeRAM), where the write and read reliability issues are exacerbated by the variations. We propose adaptive write and read schemes for highly efficient STT-MRAM and MeRAM programming and sensing that optimally selects write and read pulses to overcome process and temperature variation. With adaptive write, the write latency of STT-MRAM and MeRAM cache are reduced by up to 17% and 59% respectively, and application run time is improved by up to 41%. With adaptive read, the sensing margin is dramatically improved by 1.4X while maintaining read disturbance correctable by error-correcting-code (ECC) correction. To further mitigate read disturbance impact on memory system, additional adaptive read scheme can dynamically lower read voltage according to the proposed monitor result. It can extend memory service time by haft to one year, and reduce read disturbance induced memory failure by 59% to 84%. To better support these schemes, we also propose, design, and evaluate low-cost MTJ-based variation monitor, which precisely senses process and temperature variation. The monitor is over 10X faster, 5X more energy-efficient, and 20X smaller compared with conventional thermal monitors of similar accuracy.

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Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions

Cited by 167 publications

References 43 publications

Spin-driven electrical power generation at room temperature

Spin-driven electrical power generation at room temperature

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au_0.25Pt_0.75

Adaptive MRAM Write and Read with MTJ Variation Monitor

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Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions

Cited by 167 publications

References 43 publications

Spin-driven electrical power generation at room temperature

Spin-driven electrical power generation at room temperature

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au0.25Pt0.75

Adaptive MRAM Write and Read with MTJ Variation Monitor

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Product

Resources

About

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au_0.25Pt_0.75