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 153 publications

(103 citation statements)

References 43 publications

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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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“…Today, thin films with a thickness of tens of MLs are the basic units in magnetic recording, and the discovery of giant magnetoresistance led to a drastic increase in the sensitivity of computer hard disk read‐heads—the first examples of spintronic devices—enabling a staggering increase in the areal density of magnetic recording devices. In the past decade, magnetic tunnel junctions have been increasingly deployed in magnetic random access memory developed to industrial‐scale to enable non‐volatile memory by exploiting the reciprocal relationship between spin transfer torque and tunneling magnetoresistance …”

Section: The First Atomically Thin Magnets In Elemental Co Fe and Nimentioning

confidence: 99%

Two‐Dimensional Magnets: Forgotten History and Recent Progress towards Spintronic Applications

Cortie

Causer

Rule

et al. 2019

Adv Funct Materials

161

121

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The recent discovery of 2D magnetic order in van der Waals materials has stimulated a renaissance in the field of atomically thin magnets. This has led to promising demonstrations of spintronic functionality such as tunneling magnetoresistance. The frantic pace of this emerging research, however, has also led to some confusion surrounding the underlying phenomena of phase transitions in 2D magnets. In fact, there is a rich history of experimental precedents beginning in the 1960s with quasi-2D bulk magnets and progressing to the 1980s using atomically thin sheets of elemental metals. This review provides a holistic discussion of the current state of knowledge on the three distinct families of low-dimensional magnets: quasi-2D, ultrathin films, and van der Waals crystals. It highlights the unique opportunities presented by the latest implementation in van der Waals materials. By revisiting the fundamental insights from the field of low-dimensional magnetism, this review highlights factors that can be used to enhance material performance. For example, the limits imposed on the critical temperature by the Mermin-Wagner theorem can be escaped in three separate ways: magnetocrystalline anisotropy, long-range interactions, and shape anisotropy. Several recent experimental reports of atomically thin magnets with Curie temperatures above room temperature are highlighted.

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Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions

Cited by 153 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

Two‐Dimensional Magnets: Forgotten History and Recent Progress towards Spintronic Applications

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Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions

Cited by 153 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

Two‐Dimensional Magnets: Forgotten History and Recent Progress towards Spintronic Applications

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