Structural and magnetic properties of Cr-diluted CoFeB

Cui, Yishen; Ma, Ding; Poon, S. J.; Adl, T. Paul; Keshavarz, Sahar; Mewes, Tim; Wolf, Stuart A.; Lu, Jiwei

doi:10.1063/1.4825054

Cited by 4 publications

(2 citation statements)

References 23 publications

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“…Further, we assumed the damping constants are same as those used in Section V. One possibility of reducing the saturation magnetization of CoFeB (which is the most common material used for the MTJs) is to dilute CoFeB by adding Cr to it. It has been shown that CoFeCrB can have saturation magnetization anywhere between 1000 emu/cc to 100 emu/cc based on the percentage of Cr in the sample [44]. One should, however, be careful while dealing with materials having low saturation magnetization.…”

Section: A Predictive Scaling Trends For I-mtjsmentioning

confidence: 99%

Comprehensive Scaling Analysis of Current Induced Switching in Magnetic Memories Based on In-Plane and Perpendicular Anisotropies

Jaiswal

Fong

Roy

2016

IEEE J. Emerg. Sel. Topics Circuits Syst.

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Spin transfer torque based magnetic memories (STT-MRAMs) are leading contender for the replacement of SRAM caches. However, STT-MRAMs suffer from high write current, read/write stability conflicts and other failure mechanisms. In this paper, we present a comprehensive scaling analysis for STT-MRAMs based on in-plane and perpendicular anisotropy magnets in context to different failure mechanisms. Write failures are taken into consideration by the write current, read disturb failures by the critical current and read decision failure by the tunnel magneto-resistance scaling trends. Bit-cells comprising three different device structures-the conventional magnetic tunnel junctions (MTJs), the dual pillar MTJs (DP-MTJs) and the spin-orbit-torque based MTJs (SOT-MTJs) are investigated. We analyze the robustness of the aforementioned devices within the voltage constraints specified by ITRS. We also report predictive analysis results with futuristic material parameters. Through a coupled simulation framework consisting of spin transport and magnetization dynamics, we show that conventional MTJs would require higher voltages at scaled technology nodes. DP-MTJs, within ITRS voltage specifications, show better scalability (with larger bit-cell area). SOT-MTJs provide attractive power savings ( improvement) at a larger bit-cell area. Furthermore, our analysis indicates that among various possible improved material parameters, high interface perpendicular anisotropy shows the most promising way of achieving scalable memory cells at assumed ITRS voltages.Index Terms-Dual-pillar magnetic tunnel junction (MTJ), Landau-Lifshitz-Gilbert (LLG), readability, scaling, spin-orbittorque magnetic tunnel junction (SOT-MTJ), spin transfer torque based magnetic memories (STT-MRAMs), writability.

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Section: A Predictive Scaling Trends For I-mtjsmentioning

confidence: 99%

Comprehensive Scaling Analysis of Current Induced Switching in Magnetic Memories Based on In-Plane and Perpendicular Anisotropies

Jaiswal

Fong

Roy

2016

IEEE J. Emerg. Sel. Topics Circuits Syst.

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“…In the last years, several reports on doped CoFeB alloys have proven the potential of this approach. The introduction of Cr results in a strong reduction of M S [8][9][10], however, it is sometimes also causing an increase of the damping parameter [8]. The reduction of M S by doping CoFeB with Ni is smaller compared to a doping with Cr but it additionally leads to a reduction of α [8].…”

mentioning

confidence: 99%

CoFeAlB alloy with low damping and low magnetization as a candidate for spin transfer torque switching

Conca

Nakano

Meyer

et al. 2017

Journal of Applied Physics

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We investigate the effect of Al doping on the magnetic properties of the alloy CoFeB. Comparative measurements of the saturation magnetization, the Gilbert damping parameter α and the exchange constant as a function of the annealing temperature for CoFeB and CoFeAlB thin films are presented. Our results reveal a strong reduction of the magnetization for CoFeAlB in comparison to CoFeB. If the prepared CoFeAlB films are amorphous, the damping parameter α is unaffected by the Al doping in comparison to the CoFeB alloy. In contrast, in the case of a crystalline CoFeAlB film, α is found to be reduced. Furthermore, the x-ray characterization and the evolution of the exchange constant with the annealing temperature indicate a similar crystallization process in both alloys. The data proves the suitability of CoFeAlB for spin torque switching properties where a reduction of the switching current in comparison with CoFeB is expected.The alloy CoFeB is widely used in magnetic tunneling junctions in combination with MgO barriers due to the large magnetoresistance effect originating in the spin filtering effect [1][2][3][4]. For the application in magnetic random access memories, the switching of the magnetization of the free layer via spin transfer torque (STT) with spin polarised currents is a key technology. However, the required currents for the switching process are still large and hinder the applicability of this technique. The critical switching current density for an in-plane magnetized system is given by [5]where e is the electron charge, α is the Gilbert damping parameter, M S is the saturation magnetization, t f is the thickness of the free layer, H ext is the external field, H K is the effective anisotropy field and η is the spin transfer efficiency. From the expression it is clear that, concerning material parameters, J c0 is ruled by the product αM 2 S . For out-of-plane oriented layers, the term 2πM S vanishes and then J C0 is proportional to αM S [6]. Even in the case of using pure spin currents created by the Spin Hall effect, the required currents are proportional to factors of the form α n M S with n = 1, 1/2 [7]. A proper strategy to reduce the critical switching currents is then defined by reducing the saturation magnetization. This can be achieved by the development of new materials or the modification of known materials with promising properties. Since the compatibility with a MgO tunneling barrier and the spin filtering effect must be guaranteed together with industrial applicability, the second option is clearly an advantage by reducing M S in the CoFeB alloy. In this case, a critical point is that this reduction must not be associated with an increase of the damping parameter α.

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Improvement of soft magnetic properties and in-plane uniaxial magnetic anisotropy in FeCoAlO films fabricated by asymmetric targets

Han

et al. 2022

Appl. Phys. A

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Structural and magnetic properties of Cr-diluted CoFeB

Cited by 4 publications

References 23 publications

Comprehensive Scaling Analysis of Current Induced Switching in Magnetic Memories Based on In-Plane and Perpendicular Anisotropies

Comprehensive Scaling Analysis of Current Induced Switching in Magnetic Memories Based on In-Plane and Perpendicular Anisotropies

CoFeAlB alloy with low damping and low magnetization as a candidate for spin transfer torque switching

Improvement of soft magnetic properties and in-plane uniaxial magnetic anisotropy in FeCoAlO films fabricated by asymmetric targets

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