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We present a detailed x-ray magnetic circular dichroism (XMCD) study of the magnetic properties of Gd-doped EuO thin films, synthesized via molecular-beam epitaxy with Gd doping levels up to over 12%. The impact of Gd doping on the electronic and magnetic behavior of EuO is studied using XMCD and magnetometry. Gd doping significantly enhances the Curie temperature ( $T_{\mathrm{C}}$) from 69 K in undoped EuO to over 120 K, driven by increased carrier density, while preserving the high quality of the single-crystalline films. At higher doping levels, a plateau in $T_{\mathrm{C}}$is observed, which is attributed to the formation of Eu-Gd nearest-neighbor pairs that limit dopant activation. We also observe a distinctive “double-dome” structure in the temperature-dependent magnetization, which we attribute to both the ferromagnetic ordering of Eu $4f$moments at lower temperatures and the influence of conduction electrons via $4f\text{−}5d$exchange interactions at higher temperatures. These findings provide key insights into the mechanisms of carrier-induced magnetic transitions. Published by the American Physical Society2025 

In September of 2017, the island of Puerto Rico (PR) was devastated by a category 5 hurricane, Hurricane Maria. The island experienced complete blackout, and full restoration of the electrical system took nearly 11 months to complete. Therefore, it is of high interest to re-develop the infrastructure at the generation, transmission, and distribution levels so that it is hurricane-resilient. This paper describes the methodologies behind developing a more resilient electric infrastructure using a co-optimized expansion planning (CEP) software. First, a model of the PR electric power system was developed to perform long term CEP studies. The CEP tool developed seeks the minimum total cost of the PR system in a 2018-2038 planning horizon while exploring various levels of expansion investment options. The CEP also models the system under extreme events (i.e., hurricanes) to allow for data-driven resilience enhancement decisions. Second, the paper summarizes infrastructure visions that contain resilience investment options; the visions differ in terms of invested amounts of distributed generation and centralized resource. Lastly, key findings from these visions are reported and the CEP model performance is discussed.