Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

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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Switching of multi-state magnetic structures via domain wall propagation triggered by spin-orbit torques

Scientific Reports ◽

10.1038/s41598-019-56714-2 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 3

Author(s):

Shubhankar Das ◽

Ariel Zaig ◽

Hariharan Nhalil ◽

Liran Avraham ◽

Moty Schultz ◽

...

Keyword(s):

Domain Wall ◽

Electrical Current ◽

Magnetic Memory ◽

Spin Orbit ◽

Magnetic Structures ◽

Spintronic Devices ◽

Numerical Tools ◽

Multi Level ◽

Domain Wall Propagation ◽

Magnetic States

AbstractSpin-orbit torques emerge as a promising method for manipulating magnetic configurations of spintronic devices. Here, we show that these torques can induce a magnetization reversal via domain wall propagation which may open new ways in developing novel spintronic devices and in particular in realizing high-density multi-level magnetic memory. Our devices are bi-layer heterostructures of Ni0.8Fe0.2 on top of β-Ta patterned in the form of two or three crossing ellipses which exhibit in the crossing area shape-induced biaxial and triaxial magnetic anisotropy, respectively. We demonstrate field-free switching between discrete remanent magnetic states of the structures by spin-orbit torques induced by flowing electrical current through one of the ellipses. We note switchings induced by the coupling between the ellipses where current flowing in one ellipse triggers a reversal in a neighboring ellipse which propagates from the center outwards. Numerical tools successfully simulate the observed coupling-induced switching using experimentally extracted parameters.

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Electric field control of magnetic domain wall motion via modulation of the Dzyaloshinskii-Moriya interaction

Science Advances ◽

10.1126/sciadv.aav0265 ◽

2018 ◽

Vol 4 (12) ◽

pp. eaav0265 ◽

Cited By ~ 14

Author(s):

Tomohiro Koyama ◽

Yoshinobu Nakatani ◽

Jun’ichi Ieda ◽

Daichi Chiba

Keyword(s):

Domain Wall ◽

Electric Field ◽

Magnetic Domain ◽

Domain Wall Motion ◽

Asymmetric Structure ◽

Velocity Change ◽

Spintronic Devices ◽

Electrical Manipulation ◽

Substantial Change ◽

Moriya Interaction

We show that the electric field (EF) can control the domain wall (DW) velocity in a Pt/Co/Pd asymmetric structure. With the application of a gate voltage, a substantial change in DW velocity up to 50 m/s is observed, which is much greater than that observed in previous studies. Moreover, modulation of a DW velocity exceeding 100 m/s is demonstrated in this study. An EF-induced change in the interfacial Dzyaloshinskii-Moriya interaction (DMI) up to several percent is found to be the origin of the velocity modulation. The DMI-mediated velocity change shown here is a fundamentally different mechanism from that caused by EF-induced anisotropy modulation. Our results will pave the way for the electrical manipulation of spin structures and dynamics via DMI control, which can enhance the performance of spintronic devices.

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Theoretical Study of Field-Free Switching in PMA-MTJ Using Combined Injection of STT and SOT Currents

Micromachines ◽

10.3390/mi12111345 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1345

Author(s):

Shaik Wasef ◽

Hossein Fariborzi

Keyword(s):

Critical Current ◽

Theoretical Study ◽

Tunnel Junctions ◽

Spin Transfer Torque ◽

Spin Transfer ◽

Spin Orbit ◽

Micromagnetic Simulations ◽

Spintronic Devices ◽

Current Densities ◽

The Relationship

Field-free switching in perpendicular magnetic tunnel junctions (P-MTJs) can be achieved by combined injection of spin-transfer torque (STT) and spin-orbit torque (SOT) currents. In this paper, we derived the relationship between the STT and SOT critical current densities under combined injection. We included the damping–like torque (DLT) and field-like torque (FLT) components of both the STT and SOT. The results were derived when the ratio of the FLT to the DLT component of the SOT was positive. We observed that the relationship between the critical SOT and STT current densities depended on the damping constant and the magnitude of the FLT component of the STT and the SOT current. We also noted that, unlike the FLT component of SOT, the magnitude and sign of the FLT component of STT did not have a significant effect on the STT and SOT current densities required for switching. The derived results agreed well with micromagnetic simulations. The results of this work can serve as a guideline to model and develop spintronic devices using a combined injection of STT and SOT currents.

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Compact model of Domain Wall MTJ Driven by Spin Orbit Torque and Dzyaloshinskii–Moriya Interaction

IEEE Transactions on Magnetics ◽

10.1109/tmag.2021.3138191 ◽

2021 ◽

pp. 1-1

Author(s):

Manman Wang ◽

Yanfeng Jiang

Keyword(s):

Domain Wall ◽

Compact Model ◽

Spin Orbit ◽

Moriya Interaction

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

IEEE Magnetics Letters ◽

10.1109/lmag.2018.2801834 ◽

2018 ◽

Vol 9 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

Sumei Wang ◽

Meiyin Yang ◽

Chao Zhao

Keyword(s):

Stray Field ◽

Spin Orbit ◽

Magnetic Layers ◽

Deterministic Switching

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Current-induced manipulation of exchange bias in IrMn/NiFe bilayer structures

Nature Communications ◽

10.1038/s41467-021-26678-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jaimin Kang ◽

Jeongchun Ryu ◽

Jong-Guk Choi ◽

Taekhyeon Lee ◽

Jaehyeon Park ◽

...

Keyword(s):

Heavy Metal ◽

Domain Wall ◽

Electric Current ◽

Exchange Bias ◽

High Density ◽

Inversion Symmetry ◽

Spin Orbit ◽

Spintronic Devices ◽

Electrical Control ◽

Multi Level

AbstractThe electrical control of antiferromagnetic moments is a key technological goal of antiferromagnet-based spintronics, which promises favourable device characteristics such as ultrafast operation and high-density integration as compared to conventional ferromagnet-based devices. To date, the manipulation of antiferromagnetic moments by electric current has been demonstrated in epitaxial antiferromagnets with broken inversion symmetry or antiferromagnets interfaced with a heavy metal, in which spin-orbit torque (SOT) drives the antiferromagnetic domain wall. Here, we report current-induced manipulation of the exchange bias in IrMn/NiFe bilayers without a heavy metal. We show that the direction of the exchange bias is gradually modulated up to ±22 degrees by an in-plane current, which is independent of the NiFe thickness. This suggests that spin currents arising in the IrMn layer exert SOTs on uncompensated antiferromagnetic moments at the interface which then rotate the antiferromagnetic moments. Furthermore, the memristive features are preserved in sub-micron devices, facilitating nanoscale multi-level antiferromagnetic spintronic devices.

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The interfacial Dzyaloshinskii-Moriya interaction and spin-orbit torque driven domain wall motion in Co/Ni multi-layers with a Ptx(Ir,Au)1−x seedlayer

AIP Advances ◽

10.1063/1.5079825 ◽

2019 ◽

Vol 9 (3) ◽

pp. 035208 ◽

Cited By ~ 2

Author(s):

D. Lau ◽

V. Sokalski

Keyword(s):

Domain Wall ◽

Wall Motion ◽

Domain Wall Motion ◽

Spin Orbit ◽

Moriya Interaction

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Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

npj Computational Materials ◽

10.1038/s41524-021-00592-8 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Woo Seung Ham ◽

Abdul-Muizz Pradipto ◽

Kay Yakushiji ◽

Kwangsu Kim ◽

Sonny H. Rhim ◽

...

Keyword(s):

Heavy Metal ◽

Degrees Of Freedom ◽

Orbit Coupling ◽

Inversion Symmetry ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Band Formation ◽

Research Activities ◽

Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

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