Future prospects of MRAM technologies

Yuasa, Shinji; Fukushima, Akio; Yakushiji, Kay; Nozaki, Takayuki; Konoto, Makoto; Maehara, H.; Kubota, Hiroshi; Taniguchi, Tomohiro; Arai, Hiroko; Imamura, Hiroshi; Ando, Koji; Shiota, Yoichi; Bonell, Frédéric; Suzuki, Y.; Shimomura, N.; Kitagawa, E.; Ito, Junichi; Fujita, Shinobu; Abe, Kazutaka; Nomura, Kumiko; Noguchi, Hiroki; Yasuda, Hiroaki

doi:10.1109/iedm.2013.6724549

Cited by 56 publications

(38 citation statements)

References 19 publications

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“…Among those, the highest circular polarization (CP) value, P CP ≡ {I(σ + ) and I(σ − ) the intensity of right-and left-handed EL component, respectively, was P CP ∼ 0.3 ∼ 0.35 at RT in the external magnetic flux of B = 0.8 T, which was achieved in the context of studying the spinfiltering effect of the MgO TB (18,19). Most of the past works regarding spin-LED were carried out under the vertical arrangement with low J ranging from 0.1 to 1 A/cm 2 and forcing spins aligned vertically by applying out-of-plane external magnetic fields (20). With vertical-cavity surface-emitting laser structure incorporating the quantum wells (QWs) (21)(22)(23) or thick active layer (24) together with a means of a vertical optical resonator, pure-CP lasing was demonstrated by the optical pumping up to RT (21)(22)(23)(24).…”

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confidence: 97%

Pure circular polarization electroluminescence at room temperature with spin-polarized light-emitting diodes

Nishizawa

Nishibayashi

Munekata

2017

Proc. Natl. Acad. Sci. U.S.A.

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We report the room-temperature electroluminescence (EL) with nearly pure circular polarization (CP) from GaAs-based spinpolarized light-emitting diodes (spin-LEDs). External magnetic fields are not used during device operation. There are two small schemes in the tested spin-LEDs: first, the stripe-laser-like structure that helps intensify the EL light at the cleaved side walls below the spin injector Fe slab, and second, the crystalline AlO x spin-tunnel barrier that ensures electrically stable device operation. The purity of CP is depressively low in the low current density (J) region, whereas it increases steeply and reaches close to the pure CP when J > 100 A/cm 2 . There, either right-or left-handed CP component is significantly suppressed depending on the direction of magnetization of the spin injector. Spin-dependent reabsorption, spin-induced birefringence, and optical spin-axis conversion are suggested to account for the observed experimental results.A s well represented by the giant magnetoresistance, tunneling magnetoresistance, and spin-transfer-torque magnetic random access memory, spintronics research based on spin transport in magnetic metals has been contributing significantly in the progress of electronics through the advancement in recording bit density and low-power memory retention (1, 2). Proposal of the spin-current modulation with an electric field (3) and invention of diluted magnetic III-V semiconductors (4) have opened the opportunity of introducing spin degree of freedom in semiconductor technology (5). After those works, light-induced magnetism (6), electric-field-controlled magnetism (7), spin qubits in semiconductors (8, 9), spin-polarized light-emitting diodes (spinLEDs) (10, 11), and spin-metal-oxide-semiconductor field-effect transistor (12) were either demonstrated or proposed, which have caused an impact on the metal-based spintronics and applied physics that is not small. However, works that assure the roomtemperature (RT) operation of those semiconductor-based devices have not been accomplished to date.Concerning spin-LEDs, studies on a spin injector consisting of a ferromagnetic metal (FmM) and a tunnel barrier (TB) (13-15) succeeded those using semiconductor-based spin injectors (10, 11). The idea of the FmM-TB injector is to take advantage of spin-polarized carriers at RT with FmM and to simultaneously suppress with the TB the backward flow of unpolarized carriers that is unavoidable in the diffusive transport (16, 17). Many works have been carried out with the FmM-TB injector since then. Among those, the highest circular polarization (CP) value,) and I(σ − ) the intensity of right-and left-handed EL component, respectively, was P CP ∼ 0.3 ∼ 0.35 at RT in the external magnetic flux of B = 0.8 T, which was achieved in the context of studying the spinfiltering effect of the MgO TB (18,19). Most of the past works regarding spin-LED were carried out under the vertical arrangement with low J ranging from 0.1 to 1 A/cm 2 and forcing spins aligned vertically by applying out-of-pla...

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confidence: 97%

Pure circular polarization electroluminescence at room temperature with spin-polarized light-emitting diodes

Nishizawa

Nishibayashi

Munekata

2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Magnetic tunnel junction [1][2][3][4][5][6] with perpendicular magnetic anisotropy is one of the most promising candidates for ultra-low energy memory and logic devices such as spintransfer torque magnetic random access memories (STT-MRAM). [7][8][9][10][11][12][13][14][15][16] Among different types of perpendicular magnetic tunnel junctions (pMTJs), heavy metal (HM)/CoFeB/ MgO based structures have attracted a great deal of attention due to the advantage of having smaller STT-switching current and involving with less materials. 17 In addition, perpendicular magnetic anisotropy (PMA) in HM/CoFeB/MgO can be controlled by voltage, which could possibly lead to ultralow energy switching (<0.1 fJ) in these structures.…”

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confidence: 99%

Effect of Mo insertion layers on the magnetoresistance and perpendicular magnetic anisotropy in Ta/CoFeB/MgO junctions

Almasi

et al. 2016

Applied Physics Letters

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The effect of a thin Mo dusting layer inserted at the interface of Ta/CoFeB of perpendicular magnetic tunneling junction with MgO barriers was investigated. Unlike thick Mo layers that exhibited a strong (110) crystalline texture, the inserted Mo layer between Ta/CoFeB had little negative influence on the crystallization of CoFe (001), therefore combining the advantages of Mo as a good thermal barrier and Ta as a good boron sink. For optimized Mo dusting thickness, a large tunneling magnetoresistance of 208% was achieved in perpendicular magnetic tunneling junctions with superior thermal stability at 500 °C.

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“…A critical hurdle for traditional STT setups is the need for a spin-polarizer generating the spin current: STT devices comprise a number of ultrathin (anti)ferromagnetic, metallic, and insulating layers (see, e.g., Ref. [4]), rendering the design of architectures rather complex.…”

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confidence: 99%

Dirac spin-orbit torques and charge pumping at the surface of topological insulators

et al. 2017

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CitationNdiaye We address the nature of spin-orbit torques at the magnetic surfaces of topological insulators using the linear-response theory. We find that the so-called Dirac torques in such systems possess a different symmetry compared to their Rashba counterpart, as well as a high anisotropy as a function of the magnetization direction. In particular, the damping torque vanishes when the magnetization lies in the plane of the topological-insulator surface. We also show that the Onsager reciprocal of the spin-orbit torque, the charge pumping, induces an enhanced anisotropic damping. Via a macrospin model, we numerically demonstrate that these features have important consequences in terms of magnetization switching.

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Future prospects of MRAM technologies

Cited by 56 publications

References 19 publications

Pure circular polarization electroluminescence at room temperature with spin-polarized light-emitting diodes

Pure circular polarization electroluminescence at room temperature with spin-polarized light-emitting diodes

Effect of Mo insertion layers on the magnetoresistance and perpendicular magnetic anisotropy in Ta/CoFeB/MgO junctions

Dirac spin-orbit torques and charge pumping at the surface of topological insulators

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