Impact of Tungsten Sputtering Condition on Magnetic and Transport Properties of Double-MgO Magnetic Tunneling Junction With CoFeB/W/CoFeB Free Layer

Honjo, Haruo; Ikeda, Shoji; Sato, Hideo; Nishioka, K.; Watanabe, Tadao; Miura, S.; Nasuno, T.; Noguchi, Y.; Yasuhira, M.; Tanigawa, T.; Koike, Hideaki; Inoue, Hirofumi; Muraguchi, Masahiro; Niwa, Miki; Ohno, Hideo; Endoh, Tetsuo

doi:10.1109/tmag.2017.2701838

Cited by 20 publications

(11 citation statements)

References 13 publications

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“…As noted above, in determining the exchange constant, we have assumed that the spin S on each lattice site is the same for each sample. The varying M s t would then indicate that the effective magnetic thicknesses decrease with W insertion or that there are lower moment Fe and Co atoms at the W interfaces (i.e., what has been termed dead layers). , Another assumption that we consider in the Supporting Information is that the W layer reduces the magnetization of the entire CoFeB layer.…”

Section: Resultsmentioning

confidence: 99%

Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers

Mohammadi

Kardasz²,

Wolf³

et al. 2019

ACS Appl. Electron. Mater.

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Perpendicularly magnetized CoFeB layers with ultra-thin non-magnetic insertion layers are very widely used as the electrodes in magnetic tunnel junctions for spin transfer magnetic random access memory devices. Exchange interactions play a critical role in determining the thermal stability of magnetic states in such devices and their spin torque switching efficiency.Here the exchange constant of free layers incorporated in full magnetic tunnel junction layer stacks, specifically CoFeB free layers with W insertion layers is determined by magnetization measurements in a broad temperature range. A significant finding is that the exchange constant decreases significantly and abruptly with W insertion layer thickness. The perpendicular magnetic anisotropy shows the opposite trend; it initially increases with W insertion layer thickness and shows a broad maximum for approximately one monolayer (0.3 nm) of W. These results highlight the interdependencies of magnetic characteristics required to optimize the performance of magnetic tunnel junction devices.

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Section: Resultsmentioning

confidence: 99%

Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers

Mohammadi

Kardasz²,

Wolf³

et al. 2019

ACS Appl. Electron. Mater.

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“…Penetrated Ar may cause large stress and defects in the film, resulting in larger interdiffusion in the film. In fact, Ar was observed in W(Ar) while Kr and Xe were not in W(Kr) and W(Xe) [49].…”

Section: (1) High Thermal Tolerance By Controlling Boron Composition mentioning

confidence: 90%

“…Because it is important to suppress damage during film deposition for realization of high-performance p-MTJs, it is required to engineer a deposition process for insertion layer resulting in high TMR ratio and high perpendicular anisotropy. Therefore, we evaluated the impact of sputtering condition of W layer in the free layer and the reference layer [49,50]. By using Kr or Xe gas instead of Ar gas for W deposition, TMR ratio and perpendicular anisotropy significantly improved.…”

Section: (1) High Thermal Tolerance By Controlling Boron Composition mentioning

confidence: 99%

A Recent Progress of Spintronics Devices for Integrated Circuit Applications

Endoh

Honjo

2018

JLPEA

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Nonvolatile (NV) memory is a key element for future high-performance and low-power microelectronics. Among the proposed NV memories, spintronics-based ones are particularly attractive for applications, owing to their low-voltage and high-speed operation capability in addition to their high-endurance feature. There are three types of spintronics devices with different writing schemes: spin-transfer torque (STT), spin-orbit torque (SOT), and electric field (E-field) effect on magnetic anisotropy. The NV memories using STT have been studied and developed most actively and are about to enter into the market by major semiconductor foundry companies. On the other hand, a development of the NV memories using other writing schemes are now underway. In this review article, first, the recent advancement of the spintronics device using STT and the NV memories using them are reviewed. Next, spintronics devices using the other two writing schemes (SOT and E-field) are briefly reviewed, including issues to be addressed for the NV memories application.

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“…W is a hard metal with high melting temperature. In recent years, researchers have increased attention to adding a novel third element into the original CoFe matrix in magnetic fields [9][10][11][12][13][14]. However, few studies have focused on adding W to CoFe.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties, Adhesion, and Nanomechanical Property of Co₄₀Fe₄₀W₂₀ Films on Si (100) Substrate

Liu

Chang

et al. 2020

Journal of Nanomaterials

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In this study, a Co40Fe40W20 alloy was sputtered onto Si (100) with thicknesses (tf) ranging from 18 to 90 nm, and the corresponding structure, magnetic properties, adhesive characteristics, and nanomechanical properties were investigated. X-ray diffraction (XRD) patterns of the Co40Fe40W20 films demonstrated a significant crystalline body-centered cubic (BCC) CoFe (110) structure when the thickness was 42 nm, and an amorphous status was shown when the thickness was 18 nm, 30 nm, 60 nm, and 90 nm. The saturation magnetization (Ms) showed a saturated trend as tf was increased. Moreover, the coercivity (Hc) showed a minimum 1.65 Oe with 30 nm. Hc was smaller than 4.5 Oe owing to the small grain size distribution and amorphous structure, indicating that the Co40Fe40W20 film had soft magnetism. The low-frequency alternating current magnetic susceptibility (χac) decreased as the frequency was increased. The χac revealed a thickness effect when greater thicknesses had a large χac. The maximum χac and optimal resonance frequency (fres) of Co40Fe40W20 were investigated. The maximum χac indicated the spin sensitivity and was maximized at the optimal resonance frequency. The 90 mm thickness had the highest χac 0.18 value at an fres of 50 Hz. The contact angles of the Co40Fe40W20 films are less than 90°, which indicated that the film had a good wetting effect and hydrophilicity. The surface energy was correlated with the adhesion and displayed a concave-down trend. CoFeW films can be used as a seed or buffer layer; therefore, the surface energy and adhesion are very important. The highest surface energy was 30.12 mJ/mm2 at 42 nm and demonstrated high adhesion. High surface energy has corresponding strong adhesive performance. The increased surface roughness can induce domain wall pinning effect and high surface energy, causing a high coercivity and strong adhesion. The increase of hardness and Young’s modulus could be reasonably inferred from the thinner CoFeW films. The hardness and Young’s modulus of CoFeW films are also displayed to saturated tendency when increasing thickness.

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Impact of Tungsten Sputtering Condition on Magnetic and Transport Properties of Double-MgO Magnetic Tunneling Junction With CoFeB/W/CoFeB Free Layer

Cited by 20 publications

References 13 publications

Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers

Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers

A Recent Progress of Spintronics Devices for Integrated Circuit Applications

Magnetic Properties, Adhesion, and Nanomechanical Property of Co₄₀Fe₄₀W₂₀ Films on Si (100) Substrate

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Impact of Tungsten Sputtering Condition on Magnetic and Transport Properties of Double-MgO Magnetic Tunneling Junction With CoFeB/W/CoFeB Free Layer

Cited by 20 publications

References 13 publications

Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers

Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers

A Recent Progress of Spintronics Devices for Integrated Circuit Applications

Magnetic Properties, Adhesion, and Nanomechanical Property of Co40Fe40W20 Films on Si (100) Substrate

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Product

Resources

About

Magnetic Properties, Adhesion, and Nanomechanical Property of Co₄₀Fe₄₀W₂₀ Films on Si (100) Substrate