Domain wall propagation by spin-orbit torques in in-plane magnetized systems

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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Subsystem domination influence on magnetization reversal in designed magnetic patterns in ferrimagnetic Tb/Co multilayers

Scientific Reports ◽

10.1038/s41598-020-80004-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Łukasz Frąckowiak ◽

Feliks Stobiecki ◽

Gabriel David Chaves-O’Flynn ◽

Maciej Urbaniak ◽

Marek Schmidt ◽

...

Keyword(s):

Domain Wall ◽

Magnetization Reversal ◽

Domain Walls ◽

Compensation Point ◽

Relative Sign ◽

Reversal Process ◽

Effective Magnetization ◽

Domain Wall Propagation ◽

Characteristic Features ◽

Magnetization Reversal Process

AbstractRecent results showed that the ferrimagnetic compensation point and other characteristic features of Tb/Co ferrimagnetic multilayers can be tailored by He+ ion bombardment. With appropriate choices of the He+ ion dose, we prepared two types of lattices composed of squares with either Tb or Co domination. The magnetization reversal of the first lattice is similar to that seen in ferromagnetic heterostructures consisting of areas with different switching fields. However, in the second lattice, the creation of domains without accompanying domain walls is possible. These domain patterns are particularly stable because they simultaneously lower the demagnetizing energy and the energy associated with the presence of domain walls (exchange and anisotropy). For both lattices, studies of magnetization reversal show that this process takes place by the propagation of the domain walls. If they are not present at the onset, the reversal starts from the nucleation of reversed domains and it is followed by domain wall propagation. The magnetization reversal process does not depend significantly on the relative sign of the effective magnetization in areas separated by domain walls.

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