High Spin Torque Efficiency of Magnetic Tunnel Junctions with MgO/CoFeB/MgO Free Layer

Jan, Guenole; Wang, Yu-Jen; Moriyama, Takahiro; Lee, Yuan-Jen; Lin, Mark Chii Jeng; Zhong, Tom; Tong, Ru-Ying; Torng, Terry; Wang, Po-Kang

doi:10.1143/apex.5.093008

Cited by 84 publications

(35 citation statements)

References 25 publications

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“…The angular-momentum flow associated with the spin-polarized current from the first layer (commonly referred to as spin filtering) can be absorbed by the second ferromagnetic layer, thereby applying a spin transfer torque which can excite and even reverse its magnetization. When optimized, with nanosize contacts, these structures have magnetization switching current densities on the order of 10 10 A/m 2 giving switching currents of less than 50 μA, significantly more efficient than magnetic switching driven by a magnetic field due to a nearby current flow (often referred to as an “Oersted field”) [Jan et al ., 2012; Gajek et al ., 2012; Sato et al ., 2014]. Spin torque from a spin-polarized current can also be used to generate large-angle steady-state magnetic precession to create magnetic nano-oscillators, potentially useful for frequency-tunable microwave sources and detectors [Kiselev et al ., 2003; Silva and Rippard, 2008], to be discussed in Sec.…”

Section: Spin Transport At and Through Interfacesmentioning

confidence: 99%

Interface-induced phenomena in magnetism

et al. 2017

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This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.

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Section: Spin Transport At and Through Interfacesmentioning

confidence: 99%

Interface-induced phenomena in magnetism

et al. 2017

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“…It was recognized early that a free layer with perpendicular magnetic anisotropy (PMA) would greatly reduce the switching voltage, compared to an in-plane magnetic free layer with the same thermal stability [Slonczewski 1997, Sun 2000]. Recent rapid progress in the STT-RAM field is largely driven by breakthroughs in PMA materials [Kishi 2008, Ikeda 2010, Worledge 2011, Jan 2012. Most previous publications focused on the optimization of the free layer material, being CoFeB-based or L1 0 -based.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Tunneling Magnetoresistance in Perpendicular Magnetic Tunnel Junctions With Co|Pd Reference Layers

Topuria

Jordan-Sweet

et al. 2013

IEEE Magn. Lett.

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We report on the optimization of Co|Pd-multilayer-based reference layers in magnetic tunnel junctions with perpendicular magnetic anisotropy. By inserting a thin Ta-spacer layer between the CoFeB interfacial layer and Co|Pd multilayer, a high tunneling magnetoresistance up to 98.5% can be achieved. Electron energy loss spectroscopy and synchrotron X-ray diffraction studies show that the high magnetoresistance is related primarily to the suppression of Pd diffusion and secondarily to improved CoFeB texture during annealing.

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“…First principal calculations and many experiments [17] have proven that hybridization of Fe 3d and O 2p orbitals at the Fe\MgO interface will create a PMA in Fe. Other experiments proved that the dual layers of MgO in a MgO\CoFeB\MgO trilayer stack [18–19] could also create a PMA in CoFeB. Furthermore, Dieny [15] showed that many different oxides can also give rise to an interfacial PMA.…”

Section: Discussionmentioning

confidence: 99%

Underlayer Effect on Perpendicular Magnetic Anisotropy in Co₂₀Fe₆₀B₂₀/MgO Films

et al. 2016

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Perpendicular Magnetic Tunneling Junctions (pMTJs) with Ta\CoFeB\MgO have been extensively studied in recent years. However, the effects of the underlayer on the formation of the CoFeB perpendicular magnetic anisotropy (PMA) are still not well understood. Here we report the results of our systematic use of a wide range of elements (Ti, V, Cr, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt and Au) encompassed by columns IVA, VA, VIA, VIIA and VIIIA of the periodic table as the underlayer in a underlayer\Co20Fe60B20\MgO stack. Our goals were to survey more elements which could conceivably create a PMA in CoFeB and thereby to explore the mechanisms enabling these underlayers to enhance or create the PMA. We found underlayer elements having both an outer shell of 4d electrons (Zr, Nb Mo, and Pd) and 5d electrons (Hf, Ta, W, Re, Ir, and Pt) resulted in the development of a PMA in the MgO-capped Co20Fe60B20. Hybridization between the 3d electrons of the Fe or Co (in the Co20Fe60B20) at the interface with the 4d or 5d electrons of the underlayer is thought to be the cause of the PMA development.

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High Spin Torque Efficiency of Magnetic Tunnel Junctions with MgO/CoFeB/MgO Free Layer

Cited by 84 publications

References 25 publications

Interface-induced phenomena in magnetism

Interface-induced phenomena in magnetism

Optimization of Tunneling Magnetoresistance in Perpendicular Magnetic Tunnel Junctions With Co|Pd Reference Layers

Underlayer Effect on Perpendicular Magnetic Anisotropy in Co₂₀Fe₆₀B₂₀/MgO Films

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High Spin Torque Efficiency of Magnetic Tunnel Junctions with MgO/CoFeB/MgO Free Layer

Cited by 84 publications

References 25 publications

Interface-induced phenomena in magnetism

Interface-induced phenomena in magnetism

Optimization of Tunneling Magnetoresistance in Perpendicular Magnetic Tunnel Junctions With Co|Pd Reference Layers

Underlayer Effect on Perpendicular Magnetic Anisotropy in Co20Fe60B20/MgO Films

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Underlayer Effect on Perpendicular Magnetic Anisotropy in Co₂₀Fe₆₀B₂₀/MgO Films