In this letter, we report the visualization of topologically protected spin textures, in the form of magnetic skyrmions, in recently discovered monoatomic-thin two-dimensional CrI3. By combining density functional theory and atomistic spin dynamic simulation, we demonstrate that an application of out-of-plane electric field to CrI3 lattice favors the formation of sub-10 nm skyrmions at 0 K temperature. The spin texture arises due to a strong correlation between magneto-crystalline anisotropy, Dzyaloshinskii-Moriya interaction and the vertical electric field, whose shape and size could be tuned with the magnetic field. Such finding will open new avenues for atomic-scale quantum engineering and precision sensing.

Two-dimensional heterostructure field-effect transistors (2D-HFETs) with one-dimensional electrical contacts to atomically thin channels have recently shown great device performance, such as reduced contact resistance, leading to ballistic transport and enhanced carrier mobility. While a number of low-frequency noise studies exists on bare graphene devices supported on silicon dioxide gate insulators with surface contacts, such studies in heterostructure devices comprising epitaxial graphene on hexagonal boron nitride (hBN) with edge contacts are extremely limited. In this article, we present a systematic, temperature-dependent study of electrical transport and lowfrequency noise in edge-contacted high-mobility HFET with a single atomic-layer graphene channel encapsulated by hBN and demonstrate ultralow noise with a Hooge parameter of ≈10 −5 . By combining measurements and modeling based on underlying microscopic scattering mechanisms caused by charge carriers and phonons, we directly correlate the high-performance, temperaturedependent transport behavior of this device with the noise characteristics. Our study provides a pathway towards engineering lownoise graphene-based high-performance 2D-FETs with one-dimensional edge contacts for applications such as digital electronics and chemical/biological sensing.

We have performed micromagnetic simulations to study the formation of skyrmions from an initial single bubble domain state in ferromagnetic elements with different shapes having perpendicular anisotropy. The strength of Dzyaloshinskii-Moriya interaction (D) and uniaxial anisotropy (K) are varied to elucidate the regime in which skyrmion formation can take place. It is found that for a certain combination of D and K, skyrmion formation does not happen. Further, we also observed that for large D and small K values, finite size effect dominates, which in turn hinders the formation of typical Néel (spherical) skyrmions. However, the resulting magnetic phase is skyrmionic in nature and has different shapes. We also have found that the shape of the magnetic nano element has a significant role in determining the final magnetic state in addition to the competing D and K values.

Skyrmion racetrack memory has a lot of potential in future non-volatile solid state devices. By application of current in such devices, both spin-orbit torque and spin-transfer torques are proven to be useful to nucleate and propagate skyrmions. However, the current applied during nucleation of successive skyrmions may have unwanted perturbation viz. Joule heating and the skyrmion Hall effect, on the propagation of previously generated skyrmions. Therefore, new methodology is desired to decouple the generation and propagation of skyrmions. Here, we present a novel route via micromagnetic simulations for generation of skyrmions from triangular antidot structure in a ferromagnetic nanotrack using local Oersted field. Antidots are holes in a magnetic nanoelement. Multiple skyrmions can be simultaneously generated by incorporating a greater number of antidots. Controlled skyrmion injection can be achieved by tuning the separation between the antidots that are placed at either end of the nanotrack. Here, we propose a novel design to realise skyrmionic racetrcak memory, where one can individually generate and manipulate the skyrmions within the nanotrack.

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