magnetic skyrmions
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Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 278
Jia-Qiang Lin ◽  
Ji-Pei Chen ◽  
Zhen-Yu Tan ◽  
Yuan Chen ◽  
Zhi-Feng Chen ◽  

Magnetic skyrmions are promising potential information carriers for future spintronic devices owing to their nanoscale size, non-volatility and high mobility. In this work, we demonstrate the controlled manipulation of skyrmion motion and its implementation in a new concept of racetrack logical device by introducing an inhomogeneous perpendicular magnetic anisotropy (PMA) via micromagnetic simulation. Here, the inhomogeneous PMA can be introduced by a capping nano-island that serves as a tunable potential barriers/well which can effectively modulate the size and shape of isolated skyrmion. Using the inhomogeneous PMA in skyrmion-based racetrack enables the manipulation of skyrmion motion behaviors, for instance, blocking, trapping or allowing passing the injected skyrmion. In addition, the skyrmion trapping operation can be further exploited in developing special designed racetrack devices with logic AND and NOT, wherein a set of logic AND operations can be realized via skyrmion–skyrmion repulsion between two skyrmions. These results indicate an effective method for tailoring the skyrmion structures and motion behaviors by using inhomogeneous PMA, which further provide a new pathway to all-electric skyrmion-based memory and logic devices.

2022 ◽  
Vol 5 (1) ◽  
Jonas Spethmann ◽  
Elena Y. Vedmedenko ◽  
Roland Wiesendanger ◽  
André Kubetzka ◽  
Kirsten von Bergmann

AbstractWhen magnetic skyrmions are moved via currents, they do not strictly travel along the path of the current, instead their motion also gains a transverse component. This so-called skyrmion Hall effect can be detrimental in potential skyrmion devices because it drives skyrmions towards the edge of their hosting material where they face potential annihilation. Here we experimentally modify a skyrmion model system—an atomic Pd/Fe bilayer on Ir(111)—by decorating the film edge with ferromagnetic Co/Fe patches. Employing spin-polarized scanning tunneling microscopy, we demonstrate that this ferromagnetic rim prevents skyrmion annihilation at the film edge and stabilizes skyrmions and target states in zero field. Furthermore, in an external magnetic field the Co/Fe rim can give rise to skyrmions pinned to the film edge. Spin dynamics simulations reveal how a combination of different attractive and repulsive skyrmion-edge interactions can induce such an edge-pinning effect for skyrmions.

2022 ◽  
Vol 105 (1) ◽  
Hendrik Schrautzer ◽  
Stephan von Malottki ◽  
Pavel F. Bessarab ◽  
Stefan Heinze

2022 ◽  
Max Birch ◽  
David Cortés-Ortuño ◽  
Kai Litzius ◽  
Sebastian Wintz ◽  
Frank Schulz ◽  

Abstract Research into practical applications of magnetic skyrmions, nanoscale solitons with interesting topological and transport properties [1,2], has traditionally focused on two dimensional (2D) thin-film systems[3,4]. However, the recent observation of novel three dimensional (3D) skyrmion-like structures, such as hopfions [5], skyrmion strings (SkS) [6-9], skyrmion bundles [11] and skyrmion braids [12], motivates the investigation of new designs, aiming to exploit the third spatial dimension for more compact and higher performance spintronic devices in 3D or curvilinear geometries [13-15]. A crucial requirement of such device schemes is the control of the 3D magnetic structures via charge or spin currents, which has yet to be experimentally observed. In this work, we utilise real-space imaging to investigate the dynamics of a 3D SkS within a nanowire of Co8Zn9Mn3 at room temperature. Utilising single, nanoscale current pulses, we demonstrate current-induced nucleation of a single SkS, and a toggle-like positional switching of an individual Bloch point at the end of a SkS. The observations highlight the possibility to locally manipulate 3D topological spin textures, opening up a range of design concepts for future 3D spintronic devices.

Daniel Wolf ◽  
Sebastian Schneider ◽  
Ulrich K. Rößler ◽  
András Kovács ◽  
Marcus Schmidt ◽  

AbstractMagnetic skyrmions are stable topological solitons with complex non-coplanar spin structures. Their nanoscopic size and the low electric currents required to control their motion has opened a new field of research, skyrmionics, that aims for the usage of skyrmions as information carriers. Further advances in skyrmionics call for a thorough understanding of their three-dimensional (3D) spin texture, skyrmion–skyrmion interactions and the coupling to surfaces and interfaces, which crucially affect skyrmion stability and mobility. Here, we quantitatively reconstruct the 3D magnetic texture of Bloch skyrmions with sub-10-nanometre resolution using holographic vector-field electron tomography. The reconstructed textures reveal local deviations from a homogeneous Bloch character within the skyrmion tubes, details of the collapse of the skyrmion texture at surfaces and a correlated modulation of the skyrmion tubes in FeGe along their tube axes. Additionally, we confirm the fundamental principles of skyrmion formation through an evaluation of the 3D magnetic energy density across these magnetic solitons.

2021 ◽  
Vol 11 (1) ◽  
A. Sud ◽  
S. Tacchi ◽  
D. Sagkovits ◽  
C. Barton ◽  
M. Sall ◽  

AbstractWe show a method to control magnetic interfacial effects in multilayers with Dzyaloshinskii–Moriya interaction (DMI) using helium (He$$^{+}$$ + ) ion irradiation. We report results from SQUID magnetometry, ferromagnetic resonance as well as Brillouin light scattering results on multilayers with DMI as a function of irradiation fluence to study the effect of irradiation on the magnetic properties of the multilayers. Our results show clear evidence of the He$$^{+}$$ + irradiation effects on the magnetic properties which is consistent with interface modification due to the effects of the He$$^{+}$$ + irradiation. This external degree of freedom offers promising perspectives to further improve the control of magnetic skyrmions in multilayers, that could push them towards integration in future technologies.

2021 ◽  
Vol 13 (1) ◽  
Won-Young Choi ◽  
Woosuk Yoo ◽  
Myung-Hwa Jung

AbstractTopological spin textures such as magnetic skyrmions have attracted considerable interest due to their potential application in spintronic devices. However, there still remain several challenges to overcome before their practical application, for instance, achieving high scalability and thermal stability. Recent experiments have proposed a new class of skyrmion materials in the Heusler family, Mn1.4Pt0.9Pd0.1Sn and Mn2Rh0.95Ir0.05Sn, which possess noncollinear magnetic structures. Motivated by these experimental results, we suggest another Heusler compound hosted by Mn3Ga to overcome the above limitations. We fabricate Mn3-xPdxGa thin films, focusing on the magnetic compensation point. In Mn2.3Pd0.7Ga, we find a spin-reorientation transition around TSR = 320 K. Below the TSR, we observe the topological Hall effect and a positive magnetic entropy change, which are the hallmarks of a chiral noncollinear spin texture. By integrating all the data, we determine the magnetic phase diagram, displaying a wide chiral noncollinear spin phase even at room temperature. We believe that this compensated ferrimagnet shows promise for opening a new avenue toward chiral spin-based, high-density, and low-power devices.

2021 ◽  
Chao Chen ◽  
Tao Lin ◽  
Jianteng Niu ◽  
Yiming Sun ◽  
Liu Yang ◽  

Abstract Magnetic skyrmions, particle-like spin structures, are considered as ideal information carriers for neuromorphic computing devices due to their topological stability and nanoscale size. In this work, we proposed to control magnetic skyrmions by electric-field-excited surface acoustic waves in neuromorphic computing device structures. Our micromagnetic simulations show that the number of created skyrmions, which emulates the synaptic weight parameter, increases monotonically with increasing the amplitude of the surface acoustic waves. Additionally, the efficiency of skyrmion creation was investigated systemically with a wide range of the magnetic parameters, and the optimal values have been presented accordingly. Finally, the functionalities of short-term plasticity and long-term potentiation have been demonstrated via the skyrmion excitation by the sequence of surface acoustic waves with different intervals. The application of surface acoustic waves in the skyrmionic neuromorphic computing devices paves a novel way for low-power computing systems.

2021 ◽  
Vol 9 ◽  
Markus Hoffmann ◽  
Gideon P. Müller ◽  
Christof Melcher ◽  
Stefan Blügel

Chiral magnetic skyrmions, localized and topologically protected vortex-like magnetic textures that can be found in chiral magnets, are currently under intense study as an entity for information storage and processing. A recent study showed that so-called rank-one materials can host both skyrmions and antiskyrmions at the same energy. In such systems the Dzyaloshinskii-Moriya interaction, in general a tensorial quantity, is reduced to only one non-zero component. The presence of both skyrmions and antiskyrmions allows for the investigation of the possible interplay between them. Here, we investigate the stability and interaction of skyrmions and antiskyrmions as well as their transport properties subject to spin-orbit torque for a model system described by an atomistic spin-lattice Hamiltonian employing the simulation software Spirit. The spin-orbit torque driven spin-dynamics described by the Landau-Lifshitz-Gilbert equation is compared to the effective one of the Thiele equation. We demonstrate that, even though skyrmions and antiskyrmions can be seen as antiparticles, a rather dense arrangement of both along a memory track is possible, enabling their use as representations of the binary data bits “0” and “1” in a memory device.

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