Magnetic Direct-Write Skyrmion Nanolithography

Abstract

Magnetic skyrmions are stable spin textures with quasiparticle behavior and attract significant interest in fundamental and applied physics. The metastability of magnetic skyrmions at zero magnetic field is particularly important to enable, for instance, a skyrmion racetrack memory. Here, the results of the nucleation of stable skyrmions and formation of ordered skyrmion lattices by magnetic force microscopy in (Pt/CoFeSiB/W) n multilayers, exploiting the additive effect of the interfacial Dzyaloshinskii−Moriya interaction, are presented. The appropriate conditions under which skyrmion lattices are confined with a dense two-dimensional liquid phase are identified. A crucial parameter to control the skyrmion lattice characteristics and the number of scans resulting in the complete formation of a skyrmion lattice is the distance between two adjacent scanning lines of a magnetic force microscopy probe. The creation of skyrmion patterns with complex geometry is demonstrated, and the physical mechanism of direct magnetic writing of skyrmions is comprehended by micromagnetic simulations. This study shows a potential of a direct-write (maskless) skyrmion (topological) nanolithography with sub-100 nm resolution, where each skyrmion acts as a pixel in the final topological image.

Room-temperature skyrmion lattice in a layered magnet (Fe 0.5 Co 0.5 ) 5 GeTe 2

“…We now discuss the possible mechanisms that lead to the observation of a zero-field skyrmion lattice in the FCGT nanoflakes. In previous works, zero-field Néel-type skyrmions have been stabilized by an exchange bias field ( 39 ), stray fields from MFM tips ( 40 , 41 ), and Joule heating ( 42 – 44 ) in multilayer ferromagnetic metal films. The exchange bias scenario can be eliminated because anomalous Hall measurements on zero-field skyrmion samples exhibit no measurable shift after either positive or negative field cooling (see fig.…”

Confinement of Magnetic Skyrmions to Corrals of Artificial Surface Pits with Complex Geometries

“…Alternatively, Zhang et al [31] showed that skyrmions were directly created by scanning the surface of a specimen by a magnetic force microscopy (MFM) tip with bias field. Using the same technique, Ognev et al [32] have demonstrated the creation of zero-bias-field skyrmion patterns with complex geometries, such as a toroid and an alphabet S. In a previous study [33], we demonstrated that even tiny surface pits with nanometer-scale dimensions fabricated by using a focused electron beam (surface-pit corral) are effective to confine stable skyrmion states. These unconventional techniques have the potential advantage of facilitating complex geometries that are difficult or even not feasible by conventional microfabrication techniques.…”

Бистабильность Магнитных Скирмионов В Многослойной Структуре Ферромагнетик/Тяжелый Металл

“…Микромагнитное моделирование проводилось в программном пакете MuMax3 [15], в котором решается уравнение Ландау−Лифшица−Гильберта [16] личина взаимодействия DMI изменялась в диапазоне 0−1.2 mJ/m 2 , что согласуется с экспериментальными данными [6,[17][18][19][20][21].…”