Deterministic Switching of Perpendicularly Magnetic Layers by Spin–Orbit Torque Through Stray Field Engineering

AbstractPerpendicularly magnetized synthetic antiferromagnets (SAF), possessing low net magnetization and high thermal stability as well as easy reading and writing characteristics, have been intensively explored to replace the ferromagnetic free layers of magnetic tunnel junctions as the kernel of spintronic devices. So far, utilizing spin-orbit torque (SOT) to realize deterministic switching of perpendicular SAF have been reported while a large external magnetic field is typically needed to break the symmetry, making it impractical for applications. Here, combining theoretic analysis and experimental results, we report that the effective modulation of Dzyaloshinskii-Moriya interaction by the interfacial crystallinity between ferromagnets and adjacent heavy metals plays an important role in domain wall configurations. By adjusting the domain wall configuration between Bloch type and Néel type, we successfully demonstrate the field-free SOT-induced magnetization switching in [Co/Pd]/Ru/[Co/Pd] SAF devices constructed with a simple wedged structure. Our work provides a practical route for utilization of perpendicularly SAF in SOT devices and paves the way for magnetic memory devices with high density, low stray field, and low power consumption.

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Magnetic field-free deterministic switching of a perpendicular magnetic layer by spin-orbit torques

Spintronics XII ◽

10.1117/12.2529119 ◽

2019 ◽

Author(s):

Roberto Orio ◽

Siegfried Selberherr ◽

Viktor Sverdlov

Keyword(s):

Magnetic Field ◽

Magnetic Layer ◽

Spin Orbit ◽

Deterministic Switching

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Numerical Analysis of Deterministic Switching of a Perpendicularly Magnetized Spin-Orbit Torque Memory Cell

IEEE Journal of the Electron Devices Society ◽

10.1109/jeds.2020.3039544 ◽

2020 ◽

pp. 1-1

Author(s):

Roberto Lacerda de Orio ◽

Johannes Ender ◽

Simone Fiorentini ◽

Wolfgang Goes ◽

Siegfried Selberherr ◽

...

Keyword(s):

Numerical Analysis ◽

Memory Cell ◽

Spin Orbit ◽

Deterministic Switching

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Spin-orbit torque switching of chiral magnetization across a synthetic antiferromagnet

Communications Physics ◽

10.1038/s42005-020-00513-z ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Kang Wang ◽

Lijuan Qian ◽

See-Chen Ying ◽

Gang Xiao

Keyword(s):

Three Dimensional ◽

Magnetic Multilayers ◽

Spin Orbit ◽

Magnetic Structures ◽

Numerical Studies ◽

Synthetic Antiferromagnet ◽

Magnetic Layers ◽

Low Dimensional ◽

And Control ◽

Moriya Interaction

AbstractThe interfacial Dzyaloshinskii-Moriya interaction (DMI) holds promises for design and control of chiral spin textures in low-dimensional magnets with efficient current-driven dynamics. Recently, an interlayer DMI has been found to exist across magnetic multilayers with a heavy-metal spacer between magnetic layers. This opens the possibility of chirality in these three-dimensional magnetic structures. Here we show the existence of the interlayer DMI in a synthetic antiferromagnetic multilayer with both inversion and in-plane asymmetry. We analyse the interlayer DMI’s effects on the magnetization and the current-induced spin-orbit torque (SOT) switching of magnetization through a combination of experimental and numerical studies. The chiral nature of the interlayer DMI leads to an asymmetric SOT switching of magnetization under an in-plane magnetic field. Our work paves the way for further explorations on controlling chiral magnetizations across magnetic multilayers through SOTs, which can provide a new path in the design of SOT devices.

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Deterministic Spin–Orbit Torque Switching of a Perpendicularly Polarized Magnet Using Wedge Shape of the Magnet

SPIN ◽

10.1142/s2010324716400087 ◽

2016 ◽

Vol 06 (02) ◽

pp. 1640008

Author(s):

Debanjan Bhowmik ◽

Sayeef Salahuddin

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Data Storage ◽

Vertical Direction ◽

Anisotropy Axis ◽

Spin Orbit ◽

Micromagnetic Simulations ◽

Wedge Shape ◽

Memory Applications ◽

Deterministic Switching

Spin–orbit torque provides an efficient way to switch magnets for low power memory applications by reducing the current density needed to switch the magnetization. Perpendicularly polarized magnets are preferred for high density data storage applications because of their high thermal stability in scaled dimensions. However, spin–orbit torque cannot switch a perpendicularly polarized magnet deterministically from up to down and down to up in the absence of an external magnetic field because spin–orbit torque alone cannot break the symmetry of the system. This poses a severe challenge to the applicability of spin–orbit torque for memory devices. In this paper, we show through micromagnetic simulations that when spin–orbit torque is applied on a magnet with a wedge shape, the moments of the magnet are aligned in-plane. On removal of the spin–orbit torque the moments deterministically evolve to vertically upward or downward direction because the anisotropy axis of the magnet is tilted away from the vertical direction owing to the wedge shape of the magnet. Thus, spin–orbit torque driven deterministic switching of the magnet in the absence of an external magnetic field is possible.

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