Enhancement of perpendicular magnetic anisotropy in FeB free layers using a thin MgO cap layer

Kubota, Hiroshi; Ishibashi, S.; Saruya, Takeshi; Nozaki, Takayuki; Fukushima, Akio; Yakushiji, Kay; Ando, Koji; Suzuki, Y.; Yuasa, Shinji

doi:10.1063/1.3679393

Cited by 97 publications

(62 citation statements)

References 17 publications

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“…Recently, various solutions in the zero magnetic field case have been suggested to produce the steady-state precession, namely, STO with a perpendicularly magnetized pinned layer, 19,20 magnetic vortex oscillators, 21,22 a tilted magnetization of the fixed layer respect to the film plane, 23 and a synthetic ferromagnetic free layer. 24 Recently, the discovery of interfacial perpendicular anisotropy (IPA) between the ferromagnetic electrodes and the tunnel barrier of MTJs [25][26][27] enabled the realization of a STO with a perpendicularly magnetized free layer (PMF) and an in-plane magnetized pinned layer, which may be referred to as PMF-STO. This structure was able to exhibit a reduced threshold current, a high power and a high Q factor.…”

Section: Introductionmentioning

confidence: 99%

Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

2015

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Spin torque oscillator frequency versus magnetic field angle: The prospect of operation beyond 65 GHz Applied Physics Letters 94, 102507 (2009) We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

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Section: Introductionmentioning

confidence: 99%

Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

2015

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“…Higher Keff 26) and  27,28) in doubleinterface structure compared to single-interface structure were also reported. In this paper, we review the current status of p-MTJs with the MgO/CoFeB/Ta/CoFeB/MgO recording structure.…”

Section: Introductionmentioning

confidence: 88%

MgO/CoFeB/Ta/CoFeB/MgO recording structure with low intrinsic critical current and high thermal stability

et al. 2014

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CoFeB-MgO based magnetic tunnel junctions with perpendicular easy axis are attracting much interest for application to nonvolatile very large scale integrated circuits. MgO/CoFeB/Ta/CoFeB/MgO recording structure with double-interface shows a high thermal stability factor without an increase of intrinsic critical current with comparison to MgO/CoFeB recording structure with single-interface. In this paper, we review our recent progress on the CoFeBMgO magnetic tunnel junctions with a double MgO barrier (MgO/CoFeB/Ta/CoFeB/MgO) recording structure. It enabled us to obtain magnetic tunnel junctions with a high thermal stability factor of 59 at a device dimension of 29 nm in diameter.

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“…25) Yuasa et al experimentally demonstrated a large TMR using MgO that exceeds 100% at room temperature for the first time. 26) The use of a crystalline tunnel insulator greatly improved TMR characteristics, 27) but the on/off ratio of MTJs still remains unsatisfactory for ultimate integration. In addition, 3D integration similar to that applied in flash is inherently difficult.…”

Section: Spin-torque-transfer Mramsmentioning

confidence: 99%

Review of Emerging New Solid-State Non-Volatile Memories

Fujisaki

2013

Jpn. J. Appl. Phys.

113

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The integration limit of flash memories is approaching, and many new types of memory to replace conventional flash memories have been proposed. Unlike flash memories, new nonvolatile memories do not require storage of electric charges. The possibility of phase-change randomaccess memories (PCRAMs) or resistive-change RAMs (ReRAMs) replacing ultrahigh-density NAND flash memories has been investigated; however, many issues remain to be overcome, making the replacement difficult. Nonetheless, ferroelectric RAMs (FeRAMs) and magnetoresistive RAMs (MRAMs) are gradually penetrating into fields where the shortcomings of flash memories, such as high operating voltage, slow rewriting speed, and limited number of rewrites, make their use inconvenient. For instance, FeRAMs are widely used in ICs that require low power consumption such as smart cards and wireless tags. MRAMs are used in many kinds of controllers in industrial equipment that require high speed and unlimited rewrite operations. For successful application of new non-volatile semiconductor memories, such memories must be practically utilized in new fields in which flash memories are not applicable, and their technologies must be further developed.

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Enhancement of perpendicular magnetic anisotropy in FeB free layers using a thin MgO cap layer

Cited by 97 publications

References 17 publications

Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

MgO/CoFeB/Ta/CoFeB/MgO recording structure with low intrinsic critical current and high thermal stability

Review of Emerging New Solid-State Non-Volatile Memories

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