Intrinsic and Extrinsic Unity for Chiral-Spin Alignment and Charge-to-Spin Conversion Induced by the Rashba-Edelstein Effect.

Reducing the dimensionality in layered materials typically yields properties distinct from bulk properties. In systems with broken inversion symmetry, strong spin-orbit coupling induces relativistic electron interactions such as the Rashba-Edelstein effect (REE). Initially proposed in two-dimensional magnets, applying the REE theory to real three-dimensional systems poses challenges, necessitating experimental validation.

Additive roles of antiferromagnetically coupled elements in the magnetic proximity effect in the GdFeCo/Pt system.

Interfacial magnetic interactions between different elements are the origin of various spin-transport phenomena in multi-elemental magnetic systems. We investigate the coupling between the magnetic moments of the rare-earth, transition-metal, and heavy-metal elements across the interface in a GdFeCo/Pt thin film, an archetype system to investigate ferrimagnetic spintronics. The Pt magnetic moments induced by the antiferromagnetically aligned FeCo and Gd moments are measured using element-resolved x-ray measurements.

Sign Reversal of Spin-Transfer Torques.

Spin-transfer torque (STT) and spin-orbit torque (SOT) form the core of spintronics, allowing for the control of magnetization through electric currents. While the sign of SOT can be manipulated through material and structural engineering, it is conventionally understood that STT lacks a degree of freedom in its sign. However, this study presents the first demonstration of manipulating the STT sign by engineering heavy metals adjacent to magnetic materials in magnetic heterostructures.

Position error-free control of magnetic domain-wall devices via spin-orbit torque modulation.

Magnetic domain-wall devices such as racetrack memory and domain-wall shift registers facilitate massive data storage as hard disk drives with low power portability as flash memory devices. The key issue to be addressed is how perfectly the domain-wall motion can be controlled without deformation, as it can replace the mechanical motion of hard disk drives. However, such domain-wall motion in real media is subject to the stochasticity of thermal agitation with quenched disorders, resulting in severe deformations with pinning and tilting.

Interface Engineering of Magnetic Anisotropy in van der Waals Ferromagnet-based Heterostructures.

Interface engineering is an effective approach to tune the magnetic properties of van der Waals (vdW) magnets and their heterostructures. The prerequisites for the practical utilization of vdW magnets and heterostructures are a quantitative analysis of their magnetic anisotropy and the ability to modulate their interfacial properties, which have been challenging to achieve with conventional methods. Here we characterize the magnetic anisotropy of FeGeTe layers by employing the magnetometric technique based on anomalous Hall measurements and confirm its intrinsic nature.

Bulk Dzyaloshinskii-Moriya interaction in amorphous ferrimagnetic alloys.

Symmetry breaking is a fundamental concept that prevails in many branches of physics. In magnetic materials, broken inversion symmetry induces the Dzyaloshinskii-Moriya interaction (DMI), which results in fascinating physical behaviours with the potential for application in future spintronic devices. Here, we report the observation of a bulk DMI in GdFeCo amorphous ferrimagnets.

Low Magnetic Damping of Ferrimagnetic GdFeCo Alloys.

We investigate the Gilbert damping parameter α for rare earth (RE)-transition metal (TM) ferrimagnets over a wide temperature range. Extracted from the field-driven magnetic domain-wall mobility, α was as low as the order of 10^{-3} and was almost constant across the angular momentum compensation temperature T_{A}, starkly contrasting previous predictions that α should diverge at T_{A} due to a vanishing total angular momentum. Thus, magnetic damping of RE-TM ferrimagnets is not related to the total angular momentum but is dominated by electron scattering at the Fermi level where the TM has a dominant damping role.

Vanishing skyrmion Hall effect at the angular momentum compensation temperature of a ferrimagnet.

In the presence of a magnetic field, the flow of charged particles in a conductor is deflected from the direction of the applied force, which gives rise to the ordinary Hall effect. Analogously, moving skyrmions with non-zero topological charges and finite fictitious magnetic fields exhibit the skyrmion Hall effect, which is detrimental for applications such as skyrmion racetrack memory. It was predicted that the skyrmion Hall effect vanishes for antiferromagnetic skyrmions because their fictitious magnetic field, proportional to net spin density, is zero.

Correlation of the Dzyaloshinskii-Moriya interaction with Heisenberg exchange and orbital asphericity.

Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii-Moriya interaction (DMI) is an essential phenomenon for the formation of such chiral spin textures. In spite of recent theoretical progress aiming at understanding the microscopic origin of the DMI, an experimental investigation unravelling the physics at stake is still required.

Fast domain wall motion in the vicinity of the angular momentum compensation temperature of ferrimagnets.

Antiferromagnetic spintronics is an emerging research field which aims to utilize antiferromagnets as core elements in spintronic devices. A central motivation towards this direction is that antiferromagnetic spin dynamics is expected to be much faster than its ferromagnetic counterpart. Recent theories indeed predicted faster dynamics of antiferromagnetic domain walls (DWs) than ferromagnetic DWs.

Optimal angle of magnetic field for magnetic bubblecade motion.

Unidirectional motion of magnetic structures such as the magnetic domain and domain walls is a key concept underlying next-generation memory and logic devices. As a potential candidate of such unidirectional motion, it has been recently demonstrated that the magnetic bubblecade-the coherent unidirectional motion of magnetic bubbles-can be generated by applying an alternating magnetic field. Here we report the optimal configuration of applied magnetic field for the magnetic bubblecade.

Wide-Range Probing of Dzyaloshinskii-Moriya Interaction.

The Dzyaloshinskii-Moriya interaction (DMI) in magnetic objects is of enormous interest, because it generates built-in chirality of magnetic domain walls (DWs) and topologically protected skyrmions, leading to efficient motion driven by spin-orbit torques. Because of its importance for both potential applications and fundamental research, many experimental efforts have been devoted to DMI investigation. However, current experimental probing techniques cover only limited ranges of the DMI strength and have specific sample requirements.

Skyrmion motion driven by oscillating magnetic field.

The one-dimensional magnetic skyrmion motion induced by an electric current has attracted much interest because of its application potential in next-generation magnetic memory devices. Recently, the unidirectional motion of large (20 μm in diameter) magnetic bubbles with two-dimensional skyrmion topology, driven by an oscillating magnetic field, has also been demonstrated. For application in high-density memory devices, it is preferable to reduce the size of skyrmion.

Magnetic bubblecade memory based on chiral domain walls.

Unidirectional motion of magnetic domain walls is the key concept underlying next-generation domain-wall-mediated memory and logic devices. Such motion has been achieved either by injecting large electric currents into nanowires or by employing domain-wall tension induced by sophisticated structural modulation. Herein, we demonstrate a new scheme without any current injection or structural modulation.

Distinct universality classes of domain wall roughness in two-dimensional Pt/Co/Pt films.

We demonstrate here that the current-driven domain wall (DW) in two dimensions forms a "facet" roughness, distinctive to the conventional self-affine roughness induced by a magnetic field. Despite the different universality classes of these roughnesses, both the current- and field-driven DW speed follow the same creep law only with opposite angular dependences. Such angular dependences result in a stable facet angle, from which a single DW image can unambiguously quantify the spin-transfer torque efficiency, an essential parameter in DW-mediated nanodevices.

Square-wave cathodic stripping voltammetric analysis of RDX using mercury-film plated glassy carbon electrode.

A mercury film (MF) is prepared by an electrochemical deposition on a glassy carbon electrode (GCE), and employed for an analysis of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using square-wave stripping voltammetry (SWSV). RDX was deposited at -0.15 V (vs.