Controlled Switching of the Number of Skyrmions in a Magnetic Nanodot by Electric Fields

Abstract

through a skyrmion, its twisted spins endow these electrons with an emergent electromagnetic field, yielding a variety of unconventional magnetoelectronic phenomena, such as topological Hall effect [12] and ultralow current density for skyrmion motion. [23][24][25][26] These properties together with the nanoscale size and topological stability, make magnetic skyrmion promising potential for future highdensity, low-power-consuming magnetic memory devices. [1][2][3] Like many quasiparticles in condensed matter physics, magnetic skyrmion also has a particle-like characteristic. [1][2][3] Owing to this feature, multiple skyrmions can aggregate and dissipate in a defined geometry, which holds promise for applications beyond conventional binary memories, such as multi-level memories, [1,28,29] neuromorphic computing, [28][29][30] probabilistic computing, [31] and nano-oscillators. [32,33] In previous work, the experiment demonstrated an accumulation and dissipation of isolated skyrmions in micrometer-sized geometries using the spin-polarized pulse current. [30] However, since the skyrmion-skyrmion interaction between different Magnetic skyrmions are topological swirling spin configurations that hold promise for building future magnetic memories and logic circuits. Skyrmionic devices typically rely on the electrical manipulation of a single skyrmion, but controllably manipulating a group of skyrmions can lead to more compact and memory-efficient devices. Here, an electric-field-driven cascading transition of skyrmion clusters in a nanostructured ferromagnetic/ferroelectric multiferroic heterostructure is reported, which allows a continuous multilevel transition of the number of skyrmions in a one-by-one manner. Most notably, the transition is non-volatile and reversible, which is crucial for multi-bit memory applications. Combined experiments and theoretical simulations reveal that the switching of skyrmion clusters is induced by the strain-mediated modification of both the interfacial Dzyaloshinskii-Moriya interaction and effective uniaxial anisotropy. The results not only open up a new direction for constructing low-power-consuming, non-volatile, and multi-bit skyrmionic devices, but also offer valuable insights into the fundamental physics underlying the voltage manipulation of skyrmion clusters.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202107908.

Magnetic skyrmions: materials, manipulation, detection, and applications in spintronic devices

“…However, these manipulation techniques fail to fully exploit the properties of skyrmions clusters and the spin chirality, which are essential for their application in advanced spintronic devices. In recent breakthroughs, our research team has achieved cascaded transitions of skyrmion clusters in a nanostructured ferromagnetic/ferroelectric multiferroic heterostructure through electric field manipulation [125]. This novel approach enables precise and continuous control over the number of skyrmions, offering non-volatile and reversible transformations critical for multibit memory applications.…”

Progress in magnetic alloys with kagome structure: materials, fabrications and physical properties

“…The quest for materials that host topologically protected nano-metric spin textures, so-called magnetic skyrmions or magnetic skyrmion bubbles, continues to be fueled by the promise of novel devices. 1 Skyrmionic spin textures have mostly been observed in noncentrosymmetric crystals, such as MnSi, 2,3 FeGe, 4 FeCoSi, 5 Cu 2 OSeO 3 , 6 GaV 4 S 8 , 7 Pt/Co/Ta 8–11 and Pt/Co/Ta/MgO/CoFeB/Mo, 12 where the Dzyaloshinskii–Moriya interaction (DMI) is active. 7 In addition to noncentrosymmetric chiral magnets in which magnetic skyrmions are stabilized by the DMI, centrosymmetric materials with uniaxial magnetic anisotropy (UMA) are another family of materials that can host skyrmions.…”

Stabilization of skyrmions in two-dimensional systems with next-nearest-neighbor exchange interactions

“…In addition, the elements of Ge and Te also cause the broken inversion symmetry of the film and induce the (Dzyaloshinskii-Moriya) DM interaction. The competitions among the DM interaction, exchange interaction, and magnetic field could give rise to an isolated skyrmion or skyrmion lattices [9][10][11][12]. For bulk Fe 3 GeTe 2 , the diameter of skyrmion is relatively large due to the weak spin-orbit coupling.…”