Academic literature on the topic 'Magnetisation Manipulation'

STT (Spin Transfer Torque) can be referred to as a process of manipulation and control of spin current in the field of spintronics. When the material is ferromagnetic nanowire La0.7Sr0.3MnO3injected currents will move the domain wall with accompanying changes of spin currents. In mikromagnetik simulation shows that the application is capable of producing flow velocity or pressure of domain wall in the direction of electron flow. The domain wall pressure generating magnetization changes with increasing current density occurs. To that end, the simulation research was done in order to obtain the effect of the injection of electric current to the magnetization of the material. This phenomenon is simulated by modeling the material into the 3D geometry. The greater the current density is given the domain wall velocity or pressure on the nanowire faster so that the magnetization process is also faster. Changes in the velocity of the fastest domain wall is obtained when the material is injected with a current density as well as M-t get a graph showing oscillation pattern that is denser when the current is increased. Furthermore, the total energy analysis with variations in size diameter of 10 nm, 20 nm and 30 nm. The results show that with increasing diameter, total energy tends to increase. Keywords: spin transfer torque, La0.7Sr0.3MnO3, magnetisation, domain wall, ferromagnetic

Magnonics is an emerging field within spintronics that focuses on developing novel magnetic devices capable of manipulating information through the modification of spin waves in nanostructures with submicron size. Here, we provide a confined magnetic rectangular element to modulate the standing spin waves, by changing the saturation magnetisation (MS), exchange constant (A), and the aspect ratio of rectangular magnetic elements via micromagnetic simulation. It is found that the bulk mode and the edge mode of the magnetic element form a hybrid with each other. With the decrease in MS, both the Kittel mode and the standing spin waves undergo a shift towards higher frequencies. On the contrary, as A decreases, the frequencies of standing spin waves become smaller, while the Kittel mode is almost unaffected. Moreover, when the length-to-width aspect ratio of the element is increased, standing spin waves along the width and length become split, leading to the observation of additional modes in the magnetic spectra. For each mode, the vibration style is discussed. These spin dynamic modes were further confirmed via FMR experiments, which agree well with the simulation results.

AbstractAntiferromagnets hosting structural or magnetic order that breaks time reversal symmetry are of increasing interest for “beyond von Neumann” computing applications because the topology of their band structure allows for intrinsic physical properties, exploitable in integrated memory and logic function. One such group are the non‐collinear antiferromagnets. Essential for domain manipulation is the existence of small net moments found routinely when the material is synthesised in thin film form and attributed to symmetry‐breaking caused by spin canting, either from the Dzyaloshinskii–Moriya interaction or from strain. Although the spin arrangement of these materials makes them highly sensitive to strain, there is little understanding about the influence of local strain fields caused by lattice defects on global properties, such as magnetisation and anomalous Hall effect. This premise is investigated by examining non‐collinear films that are either highly lattice mismatched or closely matched to their substrate. In either case, edge dislocation networks are generated and for the former case these extend throughout the entire film thickness, creating large local strain fields. These strain fields allow for finite intrinsic magnetisation in seemly structurally relaxed films and influence the antiferromagnetic domain state and the intrinsic anomalous Hall effect.This article is protected by copyright. All rights reserved

AbstractThe Bloch point is a point singularity in the magnetisation configuration, where the magnetisation vanishes. It can exist as an equilibrium configuration and plays an important role in many magnetisation reversal processes. In the present work, we focus on manipulating Bloch points in a system that can host stable Bloch points—a two-layer FeGe nanostrip with opposite chirality of the two layers. We drive Bloch points using spin-transfer torques and find that Bloch points can move collectively without any Hall effect and report that Bloch points are repelled from the sample boundaries and each other. We study pinning of Bloch points at wedge-shaped constrictions (notches) in the nanostrip and demonstrate that arrays of Bloch points can be moved past a series of notches in a controlled manner by applying consecutive current pulses of different strength. Finally, we simulate a T-shaped geometry and demonstrate that a Bloch point can be moved along different paths by applying current between suitable strip ends.

(1) Nous aVO₂vons étudié la transition de phase dans le VO₂ amorphe ultrafin et son mécanisme physique : Nous avons préparé avec succès des films amorphes ultraminces (à l'échelle nanométrique) de VO₂ avec une transition de phase significative par pulvérisation magnétron et démontré la transition de phase du VO₂ amorphe - EGT. En outre, nous avons modélisé quantitativement la transition de phase du VO₂ amorphe et classé différentes épaisseurs de VO₂ en "système fort" (>5 nm) et "système fragile" (0-2 nm). Pour le système fort, les propriétés du matériau sont moins affectées par la température, et le modèle d'Arrhenius est utilisé pour décrire le transport d'électrons de la transition de phase du VO₂. Alors que pour le système fragile, les propriétés du matériau sont plus affectées par les fluctuations de température, et le modèle de Vogel-Tammann-Fulcher peut être utilisé pour l'analyse. Les résultats démontrent le mécanisme de transition de phase des matériaux amorphes et fournissent une nouvelle idée pour comprendre la transition de phase. En outre, cette méthode directe de croissance de VO₂ ultra-mince par pulvérisation magnétron est pratique et rapide, et il peut être cultivé dans le même lot avec d'autres matériaux dans l'hétérostructure, ce qui devrait promouvoir l'application de matériaux à transition de phase dans des dispositifs pratiques. (2) Nous avons exploré une méthode permettant de réguler dynamiquement le couplage d'échange entre couches par transition de phase : nous avons introduit le VO₂ dans la couche ferromagnétique/non magnétique et nous avons réussi à réaliser la transformation réversible du couplage antiferromagnétique et du couplage ferromagnétique en régulant les électrons de conduction par le MIT de VO₂. En même temps, à partir de l'analyse du changement des propriétés magnétiques, nous clarifions que le CEI induit par le VO₂ dans différents états électroniques est dominé par le RKKY et l'effet tunnel dépendant du spin. En outre, nous étudions en détail la racine physique derrière la régulation de l'IEC par le VO₂, et nous révélons le mécanisme de régulation de l'effet de spin de l'interface par la régulation des états électroniques de l'espaceur non magnétique. Cette partie du travail propose une nouvelle approche de la régulation dynamique de l'IEC, qui fournit de nouvelles idées pour l'application de l'IEC dans les dispositifs spintroniques. (3) Nous étudions la régulation dynamique du transport d'électrons chauds polarisés en spin par transition de phase : Dans une hétérostructure ferrimagnétique/non magnétique à canal de diffusion/ferromagnétique, nous introduisons du VO₂ dans le canal de diffusion pour contrôler les propriétés électriques du canal par MIT, puis nous régulons dynamiquement le transport des électrons chauds polarisés en spin générés par la désaimantation ultrarapide de GdCo. En régulant l'activation et la désactivation des électrons chauds dans le canal, nous obtenons une régulation dynamique de l'aimantation des couches ferromagnétiques adjacentes. Parallèlement, grâce aux changements de propriétés optiques introduits par le VO₂, nous avons réussi à commuter l'aimantation de matériaux ferromagnétiques sans AOS en ferrimagnétisme excité par un laser femtoseconde à impulsion unique. De plus, nous avons vérifié et analysé le mécanisme de cette modulation ultrarapide. Dans ce travail, nous utilisons le matériau de transition de phase VO₂ comme canal de diffusion avec des propriétés électriques contrôlables pour contrôler le transport des électrons chauds à travers le MIT. Les résultats montrent que les matériaux non magnétiques jouent un rôle important dans différents types d'hétérostructures
(1) We have investigated the phase transition in ultrathin amorphous VO₂ and its physical mechanism: We have successfully prepared ultrathin (nano-scale) amorphous VO₂ films with significant phase transition by magnetron sputtering and demonstrated the phase transition of amorphous VO₂ - EGT. In addition, we quantitatively modeled the phase transition of amorphous VO₂ and classified different thicknesses of VO₂ into "strong system" (>5 nm) and "fragile system" (0-2 nm). For the strong system, the material properties are less affected by temperature, and the Arrhenius model is used to describe the electron transport of VO₂ phase transition. While for the fragile system, the material properties are more affected by temperature fluctuations, and the Vogel-Tammann-Fulcher model can be used for analysis. The results demonstrate the phase transition mechanism of amorphous materials and provide a new idea for understanding phase transition. In addition, this direct method of growing ultrathin VO₂ using magnetron sputtering is convenient and fast, and it can be grown in the same batch with other materials within the heterostructure, which is expected to promote the application of phase transition materials in practical devices.(2) We explored a method to dynamically regulate the interlayer exchange coupling by phase transition: we introduced the VO₂ into the ferromagnetic/nonmagneticspacer/ferromagnetic heterostructure, and successfully realized the reversible transformation of the antiferromagnetic coupling and ferromagnetic coupling through regulating conduction electrons by MIT of VO₂. At the same time, from the analysis of the change of magnetic properties, we clarify that the IEC induced by VO₂ in different electronic states is dominated by the RKKY and spin dependent tunneling. Furthermore, we fully investigate the physical root behind the regulation of IEC by the VO₂, and reveal the regulation mechanism of the interface spin effect by the regulation of electronic states of non-magnetic spacer. This part of the work proposes a novel approach to the dynamic regulation of IEC, which provides new ideas for the application of IEC in spintronic devices.(3) We study the dynamic regulation of spin-polarized hot electron transport by phase transition: In a ferrimagnetic/nonmagnetic diffusion channel/ferromagnetic heterostructure, we introduce VO₂ into the diffusion channel to control the electrical properties of the channel by MIT, and then dynamically regulate the transport of spin-polarized hot electrons generated by the ultrafast demagnetization of GdCo. By regulating the on/off of hot electrons in the channel, we achieve dynamic regulation of the magnetization of adjacent ferromagnetic layers. Meanwhile, with the optical property changes introduced by VO₂, we have successfully achieved the switching of the magnetization of ferromagnetic materials without AOS in ferrimagnetism excited by a single-pulse femtosecond laser. Furthermore, we have verified and analyzed the mechanism of this ultrafast modulation. In this work, we use the phase transition material VO₂ as a diffusion channel with controllable electrical properties to control the hot electron transport through MIT. The results show that the non-magnetic materials play an important role in various types of heterostructures