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Creating materials that do not exist in nature can lead to breakthroughs in science and technology. Magnetic skyrmions are topological excitations that have attracted great attention recently for their potential applications in low power, ultrahigh density memory. A major challenge has been to find materials that meet the dual requirement of small skyrmions stable at room temperature. Here we meet both these goals by developing epitaxial FeGe films with excess Fe using atomic layer molecular beam epitaxy (MBE) far from thermal equilibrium. Our atomic layer design permits the incorporation of 20% excess Fe while maintaining a non-centrosymmetric crystal structure supported by theoretical calculations and necessary for stabilizing skyrmions. We show that the Curie temperature is well above room temperature, and that the skyrmions have sizes down to 15 nm as imaged by Lorentz transmission electron microscopy (LTEM) and magnetic force microscopy (MFM). The presence of skyrmions coincides with a topological Hall effect-like resistivity. These atomically tailored materials hold promise for future ultrahigh density magnetic memory applications.

Nanowire AlGaN III‐nitride LEDs are claimed as potential high‐efficiency solid‐state photon sources spanning to the short‐wavelength deep ultraviolet (UV). Nanowire LEDs (NWLEDs) emitting in the UV are compared with a transparent n‐AlGaN top electrode formed by coalescing the top region of nanowire–ensemble LEDs with commonly employed opaque conformal metallic electrodes used for nanowire‐based devices. The use of a transparent contact results in an increase in the wall plug efficiency of >25×, exceeding the expected increase due to enhanced photon‐extraction efficiency. Increased nanowire connectivity reduces the short‐circuit pathways, enabling higher device yields of relatively large‐area (>1 mm²) UV nanowire–ensemble LEDs. Despite these large relative improvements, the absolute output efficiency remains miniscule (<1 m%). Electroluminescence microscopy demonstrates that <0.1% of nanowires within the ensemble contribute to emission. The single‐nanowire efficiency is estimated and points toward improvement of the homogeneity of the injection current as a crucial step for realizing commercially viable UV NWLEDs.