Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures

Wen, Zhenchao; Sukegawa, Hiroaki; Seki, Takeshi; Kubota, Takahide; Takanashi, Kōki; Mitani, Seiji

doi:10.1038/srep45026

Cited by 43 publications

(26 citation statements)

References 45 publications

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“…In addition to ultrathin epitaxial films with large PMA [35,59,60,61,62,63,64,65,66,67], VCMA effects have been observed in various materials systems, for example, in sputter-deposited CoFeB [68,69,70,71,72,73,74,75,76,77,78,79,80,81], which is an important practical material that is used in the mass production of MTJs, and in self-assembled nano-islands [82], nanocomposite structures [83], and ultrathin layers with quantum well states [84]. The VCMA effect can also be applied for the control of domain wall motion [85,86,87] and magnetic skyrmions [88,89,90].…”

Section: Overview Of the Vcma Effect And Voltage-induced Dynamic Smentioning

confidence: 99%

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

et al. 2019

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The electron spin degree of freedom can provide the functionality of “nonvolatility” in electronic devices. For example, magnetoresistive random access memory (MRAM) is expected as an ideal nonvolatile working memory, with high speed response, high write endurance, and good compatibility with complementary metal-oxide-semiconductor (CMOS) technologies. However, a challenging technical issue is to reduce the operating power. With the present technology, an electrical current is required to control the direction and dynamics of the spin. This consumes high energy when compared with electric-field controlled devices, such as those that are used in the semiconductor industry. A novel approach to overcome this problem is to use the voltage-controlled magnetic anisotropy (VCMA) effect, which draws attention to the development of a new type of MRAM that is controlled by voltage (voltage-torque MRAM). This paper reviews recent progress in experimental demonstrations of the VCMA effect. First, we present an overview of the early experimental observations of the VCMA effect in all-solid state devices, and follow this with an introduction of the concept of the voltage-induced dynamic switching technique. Subsequently, we describe recent progress in understanding of physical origin of the VCMA effect. Finally, new materials research to realize a highly-efficient VCMA effect and the verification of reliable voltage-induced dynamic switching with a low write error rate are introduced, followed by a discussion of the technical challenges that will be encountered in the future development of voltage-torque MRAM.

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Section: Overview Of the Vcma Effect And Voltage-induced Dynamic Smentioning

confidence: 99%

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

et al. 2019

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“…There are several possible mechanisms affecting the uniaxial anisotropy constant. A first one is a direct voltage induced variation of anisotropy due to interfacial charge modulation [27][28][29][30], but this effect is relatively weak compared to the influence of the temperature variation associated with Joule heating. A second mechanism -is a temperature induced variation of the anisotropy due to Joule heating, which is the most significant for our samples.…”

Section: Modelmentioning

confidence: 99%

Impact of Joule heating on the stability phase diagrams of perpendicular magnetic tunnel junctions

et al. 2018

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Measured switching voltage-field (V-H) diagrams of perpendicular magnetic tunnel junctions (pMTJ) exhibit unexpected behavior at high voltages associated with significant heating of the storage layer. The boundaries deviate from the critical lines corresponding to the coercive field, which contrasts with the theoretically predicted behavior of a standard macrospin-based model. Combining recent experimental studies of the temperature dependence of spin polarization and perpendicular magnetic anisotropy (PMA) we are proposing a modified model. Our approach takes into account the Joule heating during the writing pulse, which reduces the spin polarization and the anisotropy, thereby reducing the spin torque efficiency and the coercive field during the switching. The numerical macrospin simulations based on this model are in agreement with our experimental measurements and consistent with the results derived from the linearization of Landau-Lifshitz-Gilbert equation.

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“…Indeed, electric field control, or electrocontrol, of magnetism has been an issue deserving full commitment. Fortunately, electric field controlled magnetic anisotropy has been experimentally revealed in magnetic heterostructures [20][21][22][23], and the anisotropy gradient can be obtained through an elaborate structure design such as wedged heterostructures [24]. Under such a gradient, the AFM domain wall tends to move towards the low anisotropy side in order to reduce the free energy.…”

Section: Introductionmentioning

confidence: 99%

Ultralow-loss domain wall motion driven by a magnetocrystalline anisotropy gradient in an antiferromagnetic nanowire

Wen

Chen

et al. 2020

Phys. Rev. Research

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Searching for a new scheme to control the antiferromagnetic (AFM) domain wall is one of the most important issues for AFM spintronic devices. In this work, we study theoretically the domain wall motion of an AFM nanowire, driven by the axial anisotropy gradient generated by an external electric field and an electrocontrol of AFM domain wall motion in the merit of ultralow energy loss is demonstrated. The domain wall velocity depending on the anisotropy gradient magnitude and intrinsic material properties is simulated based on the Landau-Lifshitz-Gilbert equation and also deduced using the energy dissipation theorem. It is shown that the domain wall moves at a nearly constant speed for the small anisotropy gradient, and this motion is accelerated for the large gradient due to the enlarged domain wall width. While the domain wall mobility is independent of the lattice dimension and types of the domain wall, it can be enhanced by the Dzyaloshinskii-Moriya interaction. In addition, the physical mechanism for much faster AFM wall dynamics than ferromagnetic wall dynamics is qualitatively explained. This work unveils a promising strategy for controlling the AFM domain walls, benefiting the future of AFM spintronic applications.

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Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures

Cited by 43 publications

References 45 publications

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

Impact of Joule heating on the stability phase diagrams of perpendicular magnetic tunnel junctions

Ultralow-loss domain wall motion driven by a magnetocrystalline anisotropy gradient in an antiferromagnetic nanowire

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