Diffusion behavior of the spin valve structure

Huang, Rong-Tan; Chen, Fu‐Rong; Kai, Ji‐Jung; Tsu, I-Fei; Mao, Sining; Kai, Wu

doi:10.1063/1.1357129

Cited by 11 publications

(7 citation statements)

References 7 publications

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“…In this case, the sample's composition is Sub:=Tað5Þ=Ruð50Þ= Tað5Þ = NiFeð5Þ = IrMnð8Þ = CoFeð2.5Þ = Ruð2.5Þ = CoFeBð3Þ= MgOð1.7Þ=CoFeBð3Þ=Tað5Þ=Ruð15Þ. From earlier work on spin valves, Ru is known to be a fairly good diffusion barrier for Mn (Huang et al, 2001). Thanks to the reduced Mn diffusion compared to the previous structure, the TMR was found to increase as a function of annealing temperature up to 430°C, producing a TMR amplitude of up to 360% of preannealed values.…”

Section: Influence Of Annealing a Controlling The Diffusion Of Atomimentioning

confidence: 99%

Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications

2017

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International audienceSpin electronics is a rapidly expanding field stimulated by a strong synergy between breakthrough basic research discoveries and industrial applications in the fields of magnetic recording, magnetic field sensors, nonvolatile memories [magnetic random access memories (MRAM) and especially spin-transfer-torque MRAM (STT-MRAM)]. In addition to the discovery of several physical phenomena (giant magnetoresistance, tunnel magnetoresistance, spin-transfer torque, spin-orbit torque, spin Hall effect, spin Seebeck effect, etc.), outstanding progress has been made on the growth and nanopatterning of magnetic multilayered films and nanostructures in which these phenomena are observed. Magnetic anisotropy is usually observed in materials that have large spin-orbit interactions. However, in 2002 perpendicular magnetic anisotropy (PMA) was discovered to exist at magneticmetal/oxide interfaces [for instance Co(Fe)/alumina]. Surprisingly, this PMA is observed in systems where spin-orbit interactions are quite weak, but its amplitude is remarkably large—comparable to that measured at Co/Pt interfaces, a reference for large interfacial anisotropy (anisotropy ∼1.4 erg/cm2 = 1.4 mJ/m2). Actually, this PMA was found to be very common at magnetic metal/oxide interfaces since it has been observed with a large variety of amorphous or crystalline oxides, including AlOx, MgO, TaOx, HfOx, etc. This PMA is thought to be the result of electronic hybridization between the oxygen and the magnetic transition metal orbit across the interface, a hypothesis supported by ab initio calculations. Interest in this phenomenon was sparked in 2010 when it was demonstrated that the PMA at magnetic transition metal/oxide interfaces could be used to build out-of-plane magnetized magnetic tunnel junctions for STT-MRAM cells. In these systems, the PMA at the CoFeB/MgO interface can be used to simultaneously obtain good memory retention, thanks to the large PMA amplitude, and a low write current, thanks to a relatively weak Gilbert damping. These two requirements for memories tend to be difficult to reconcile since they rely on the same spin-orbit coupling. PMA-based approaches have now become ubiquitous in the designs for perpendicular STT-MRAM, and major microelectronics companies are actively working on their development with the first goal of addressing embedded FLASH and static random access memory-type of applications. Scalability of STT-MRAM devices based on this interfacial PMA is expected to soon exceed the 20-nm nodes. Several very active new fields of research also rely on interfacial PMA at magnetic metal/oxide interfaces, including spin-orbit torques associated with Rashba or spin Hall effects, record high speed domain wall propagation in buffer/magnetic metal/oxide-based magnetic wires, and voltage-based control of anisotropy. This review deals with PMA at magnetic metal/oxide interfaces from its discovery, by examining the diversity of systems in which it has been observed and the physicochemical methods through which the ...

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Section: Influence Of Annealing a Controlling The Diffusion Of Atomimentioning

confidence: 99%

Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications

2017

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“…2,3,8,11,14,16 A thicker Ru layer of 1.7 nm is chosen to study the TMR at high annealing temperatures ͑above 350°C͒ and long annealing times due to its presence as a diffusion barrier of Mn. 17 However, thicknesses less than 1 nm would improve coupling in the SAF and increase the magnitude of the three characteristic fields, including H ex . 14,16 Thus, the amount of magnetic noise near zero field due to the reference layer would be decreased.…”

Section: And Plottedmentioning

confidence: 99%

Magnetic noise evolution in CoFeB/MgO/CoFeB tunnel junctions during annealing

Stearrett

Wang

Shah

et al. 2010

Applied Physics Letters

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Magnetic 1/f noise is compared in magnetic tunnel junctions with electron-beam evaporated and sputtered MgO tunnel barriers in the annealing temperature range 350-425 C. The variation of the magnetic noise parameter (a mag) of the reference layer with annealing temperature mainly reflects the variation of the pinning effect of the exchange-bias layer. A reduction in a mag with bias is associated with the bias dependence of the tunneling magnetoresistance. The related magnetic losses are parameterized by a phase lag e, which is nearly independent of bias especially below 100 mV. The similar changes in magnetic noise with annealing temperature and barrier thickness for two types of MgO magnetic tunnel junctions indicate that the barrier layer quality does not affect the magnetic losses in the reference layer. V C 2012 American Institute of Physics.

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“…One of the most sensitive techniques for measuring interdiffusion is by modulated film, i.e., the use of multilayer structures and the study of the decay of satellite peaks in x-ray reflectometry [3][4][5] even though other techniques are emerging such as the use of transmission electron microscopy ͑TEM͒ and imaging filtering. 6 The theory of interdiffusion in artificial compositionally modulated materials is well developed, and in its simplest form, the equations are linearized by treating several parameters as composition independent. 7 This is the most sensitive technique available for measuring diffusivities as low as 10 Ϫ27 m 2 /s in multilayers with modulation period of a few nanometers.…”

Section: Introductionmentioning

confidence: 99%

Interdiffusion in CoFe/Cu multilayers and its application to spin-valve structures for data storage

Svedberg

Howard

Bønsager

et al. 2003

Journal of Applied Physics

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Spin-valve structures might be exposed to higher temperatures in future disk drive applications and might thus degrade faster than it does today if proper materials and methods are not used. In order to determine whether this degradation is due to interdiffusion between constituent layers or is dominated by other phenomena, the interdiffusion coefficients for all layers in the spin valve have to be determined. For diffusion driven degradation it would then be possible to predict lifetimes based on a maximum allowed reduction in ⌬R/R where R is the resistivity. Here we report the initial results for a CoFe/Cu interface, common to many spin-valve structures. Interdiffusion in (111) textured polycrystalline CoFe/Cu multilayers has been measured and quantified by x-ray reflectometry. Bulk diffusion is dominant at temperatures above ϳ540°C and is described by an activation energy of E a ϭ2.41 eV and a prefactor of D 0 ϭ2.92ϫ10 Ϫ8 m 2 /s. Below temperature of 540°C grain boundary diffusion dominates and is characterized by E a ϭ0.90 eV and D 0 ϭ1.91 ϫ10 Ϫ17 m 2 /s. Prior to stabilization of the diffusion process there is an initial rapid change in the (111) texture. During initial ''sharpening'' of the CoFe/Cu multilayer interfaces there is shortening of the periodicity as well as a decrease in out-of-plane lattice spacing.

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Diffusion behavior of the spin valve structure

Cited by 11 publications

References 7 publications

Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications

Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications

Magnetic noise evolution in CoFeB/MgO/CoFeB tunnel junctions during annealing

Interdiffusion in CoFe/Cu multilayers and its application to spin-valve structures for data storage

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