Electrical manipulation of antiferromagnetic easy axis in IrMn/NiFe exchange-biased structures

Abstract Electrical control of antiferromagnetic moment is a key technology of antiferromagnet-based spintronics, which promises favourable device characteristics of ultrafast operation and high-density integration compared to conventional ferromagnet-based devices. To date, the manipulation of antiferromagnetic moments 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 electrical manipulation of the antiferromagnetic easy axis in IrMn/NiFe bilayers without a heavy metal. We show that the direction of the antiferromagnetic easy axis and associated exchange bias is gradually modulated between up to ±22 degrees by in-plane current, which is independent of the NiFe thickness, however. This suggests that spin currents arising in the IrMn layer exert SOTs on uncompensated antiferromagnetic moments at the interface and then rotate the antiferromagnetic moments coherently. Furthermore, the memristive features are preserved in sub-micron devices, facilitating nanoscale multi-level antiferromagnetic spintronic devices.

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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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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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Giant Dzyaloshinskii-Moriya interaction in Rashba superlattices

10.21203/rs.3.rs-39851/v1 ◽

2020 ◽

Author(s):

Woo-Seung Ham ◽

Abdul-Muizz Pradipto ◽

Kay Yakushiji ◽

Kwangsu Kim ◽

Sonny Rhim ◽

...

Keyword(s):

Heavy Metal ◽

Material Design ◽

Orbit Coupling ◽

Inversion Symmetry ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Band Formation ◽

Stacking Order ◽

Magnetic Skyrmions ◽

Moriya Interaction

Abstract Dzyaloshinskii-Moriya interaction (DMI) is considered as one of the most important energy for specific chiral texture such as magnetic skyrmions. The key of generating DMI is absence of structural inversion symmetry and exchange energy with spin-orbit coupling. Therefore, a vast majority of researches about DMI is mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report that asymmetric band formation in an artificial superlattice arises from inversion symmetry breaking in stacking order of atomic layers, resulting in bulk DMI. 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. Such Rashba superlattices can be a new class of material design for spintronics applications.

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Spin-orbit torque switching of an antiferromagnetic metallic heterostructure

Nature Communications ◽

10.1038/s41467-020-19511-4 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Samik DuttaGupta ◽

A. Kurenkov ◽

Oleg A. Tretiakov ◽

G. Krishnaswamy ◽

G. Sala ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Electrical Transport ◽

Spin Orbit ◽

Practical Realization ◽

X Ray ◽

Spintronic Devices ◽

Antiferromagnetic Materials ◽

Polycrystalline Metals ◽

X Ray Imaging ◽

Electrical Manipulation

Abstract The ability to represent information using an antiferromagnetic material is attractive for future antiferromagnetic spintronic devices. Previous studies have focussed on the utilization of antiferromagnetic materials with biaxial magnetic anisotropy for electrical manipulation. A practical realization of these antiferromagnetic devices is limited by the requirement of material-specific constraints. Here, we demonstrate current-induced switching in a polycrystalline PtMn/Pt metallic heterostructure. A comparison of electrical transport measurements in PtMn with and without the Pt layer, corroborated by x-ray imaging, reveals reversible switching of the thermally-stable antiferromagnetic Néel vector by spin-orbit torques. The presented results demonstrate the potential of polycrystalline metals for antiferromagnetic spintronics.

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Time-Resolved Detection of Multilevel Switching of the Magnetization and Exchange Bias Driven by Spin-Orbit Torques

10.21203/rs.3.rs-882472/v1 ◽

2021 ◽

Author(s):

Yuyan Wang ◽

Takuya Taniguchi ◽

Po-Hung Lin ◽

Daniel Zicchino ◽

Andreas Nickl ◽

...

Keyword(s):

Current Pulse ◽

Exchange Bias ◽

High Speed ◽

Great Promise ◽

Spin Orbit ◽

Magnetization Switching ◽

Time Resolved ◽

Micromagnetic Simulations ◽

Spintronic Devices ◽

Open Questions

Abstract Current induced magnetization switching, jointly with the manipulation of exchange bias, via spin-orbit torques (SOT) on sub-nanosecond timescales hold great promise for fast and low-power spintronic devices. Specifically, the time-resolved detection and subsequent analysis of switching trajectories relevant to ferromagnet/antiferromagnet exchange biased structures are central to designing SOT devices with high speed, and are still open questions. Here, we report the SOT-induced multileveled switching on sub-nanosecond timescales in Pt/Co/IrMn heterostructures, and illustrate the time-resolved magnetization switching trajectories of the exchange bias. By adopting time-resolved magneto-optical Kerr microscopy combined with micromagnetic simulations, our work reveals that not only the ferromagnets, but also the multiple antiferromagnetic domains and exchange bias, can be partially switched by sub-nanosecond current pulse, to flexibly control the switching probabilities at multiple levels. The experiments demonstrate that the SOT switching of exchange bias, which immediately depends on the current density, can significantly stabilize the multileveled magnetization switching within sub-nanosecond current pulse with high thermal stability.

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

Nature Communications ◽

10.1038/s41467-021-23414-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ruyi Chen ◽

Qirui Cui ◽

Liyang Liao ◽

Yingmei Zhu ◽

Ruiqi Zhang ◽

...

Keyword(s):

Domain Wall ◽

Tunnel Junctions ◽

Low Power Consumption ◽

Stray Field ◽

Magnetic Memory ◽

Spin Orbit ◽

Theoretic Analysis ◽

Spintronic Devices ◽

Deterministic Switching ◽

Moriya Interaction

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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