Resistivity measurement of ZnO:AI films for solar cell

Aluminium doped Zinc Oxide films were deposited on glass slide by RF magnetron sputtering using a ZnO target mixed with A120J. All the films were growth in room temperature without intentional heating. The resistivity of the ZnO:AI films were measured using van der Pauw method in terms of the preparation conditions such as RF power, working pressure, deposition time, O2 content in sputtering gas and target-substrate distance. Resistivity of the deposited films shows the following behaviours: decreases with the increasing RF power and film thickness while increase with increasing target substrate distance, and O2 content in sputtering gas. Resistivity for films prepared in different working pressure decreases with the Argon pressure but increased after the optimal pressure of 45mTorr

Visualizing the strongly reshaped skyrmion Hall effect in multilayer wire devices.

Magnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds. Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). While promising, their dynamic phenomenology with current, skyrmion size, geometric effects and disorder remain to be established. Here we report on the ensemble dynamics of individual skyrmions forming dense arrays in Pt/Co/MgO wires by examining over 20,000 instances of motion across currents and fields. The skyrmion speed reaches 24 m/s in the plastic flow regime and is surprisingly robust to positional and size variations. Meanwhile, the SkHE saturates at ∼22∘, is substantially reshaped by the wire edge, and crucially increases weakly with skyrmion size. Particle model simulations suggest that the SkHE size dependence - contrary to analytical predictions - arises from the interplay of intrinsic and pinning-driven effects. These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices

All-Electrical Skyrmionic Bits in a Chiral Magnetic Tunnel Junction

Topological spin textures such as magnetic skyrmions hold considerable promise as robust, nanometre-scale, mobile bits for sustainable computing. A longstanding roadblock to unleashing their potential is the absence of a device enabling deterministic electrical readout of individual spin textures. Here we present the wafer-scale realization of a nanoscale chiral magnetic tunnel junction (MTJ) hosting a single, ambient skyrmion. Using a suite of electrical and multi-modal imaging techniques, we show that the MTJ nucleates skyrmions of fixed polarity, whose large readout signal - 20-70% relative to uniform states - corresponds directly to skyrmion size. Further, the MTJ exploits complementary mechanisms to stabilize distinctly sized skyrmions at zero field, thereby realizing three nonvolatile electrical states. Crucially, it can write and delete skyrmions using current densities 1,000 times lower than state-of-the-art. These results provide a platform to incorporate readout and manipulation of skyrmionic bits across myriad device architectures, and a springboard to harness chiral spin textures for multi-bit memory and unconventional computing.Comment: 8 pages, 5 figure

In-situ study of skyrmions at high resolution using differential phase contrast microscopy

Magnetic skyrmions are nanoscale topological spin structures that show great potential in future spintronic technology. In particular, skyrmions in multilayer systems open up the avenue to controlling and varying skyrmion properties for functional devices. Co/Pt-based multilayer systems have been shown to host magnetic skyrmions at room temperature, while incorporation of Ir and Fe further offers a materials platform with tunable magnetic properties [1]. In our previous studies on Ir/Fe/Co/Pt multilayers, we used Lorentz transmission electron microscopy (TEM) to characterize the chirality, formation mechanism, and evolution of room-temperature skyrmions [2]. This is the most direct imaging method for in-situ TEM studies of magnetic processes. However, as we work with multilayer films approaching the ultrathin (1 nm) limit, highly defocused Lorentz TEM images (Figure 1) prove limiting in both spatial resolution and magnetic sensitivity.Agency for Science, Technology and Research (A*STAR)We acknowledge funding from the A*STAR RIE2020 grant "Spin-Orbit Technologies for Intelligence at the Edge"

Unveiling the Emergent Traits of Chiral Spin Textures in Magnetic Multilayers.

Magnetic skyrmions are topologically wound nanoscale textures of spins whose ambient stability and electrical manipulation in multilayer films have led to an explosion of research activities. While past efforts focused predominantly on isolated skyrmions, recently ensembles of chiral spin textures, consisting of skyrmions and magnetic stripes, are shown to possess rich interactions with potential for device applications. However, several fundamental aspects of chiral spin texture phenomenology remain to be elucidated, including their domain wall (DW) structure, thermodynamic stability, and morphological transitions. Here the evolution of these textural characteristics are unveiled on a tunable multilayer platform-wherein chiral interactions governing spin texture energetics can be widely varied-using a combination of full-field electron and soft X-ray microscopies with numerical simulations. With increasing chiral interactions, the emergence of Néel helicity, followed by a marked reduction in domain compressibility, and finally a transformation in the skyrmion formation mechanism are demonstrated. Together with an analytical model, these experiments establish a comprehensive microscopic framework for investigating and tailoring chiral spin texture character in multilayer films