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Nanoscale surface morphologies generated by ultrashort laser pulses are products of a complex interplay of laser energy deposition, pressure generation, melt dynamics, and rapid resolidification. In this work, we investigate the physical factors controlling the formation of laser-induced surface nanostructures using a combined data-driven and physics-based approach. A machine learning (ML) model is developed to predict the number density of surface nanoprotrusions formed during single-pulse laser processing of metals, using a compact set of physically motivated dimensionless descriptors derived via dimensional analysis. These descriptors capture key stages of surface morphology generation, including energy deposition, pressure buildup, liquid filament breakup, and solidification. The ML model is trained on quantitative features extracted from experimental scanning electron microscopy images spanning 39 data points across nine metals. Post hoc model explanation analysis identifies the absorbed fluence and the Ohnesorge number as the most influential descriptors. The electron-phonon coupling strength emerges as a key material parameter through its control of the effective energy deposition depth and the characteristic length scale of transient liquid structures. These trends are further examined using large-scale two-temperature molecular dynamics simulations, which confirm the predicted sensitivity of surface morphology to electron–phonon coupling near the spallation threshold. 

The Seebeck coefficient of Ni–Fe, the metallic alloy proposed for active cooling applications, shows a higher Seebeck coefficient compared to its constituent elements and demonstrates agreement between ML predictions and experimental results. 

Abstract 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.