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The non-local spin valve (NLSV) is a useful device for studying spin transport at nanoscopic dimensions, with potential technological applications. Despite this appeal, background signals, unrelated to spin diffusion, often hinder the interpretation of spin signals in NLSVs and could compromise performance in future devices. In this paper, we comprehensively investigate these background signals in all-metallic NLSVs fabricated from a variety of ferromagnetic (FM; , Fe, Co) and nonmagnetic (NM; Al, Cu) metals. We demonstrate that a background signal emerges in AC measurements, with contributions from both current spreading and thermoelectric effects, with a complex dependence on both temperature and FM injector-detector separation. Despite the complexity of these dependencies, we demonstrate excellent agreement with three-dimensional finite-element modelling that accounts for current-spreading and thermoelectric effects, across a wide range of temperatures, FM separations, and FM/NM pairings. This approach additionally offers a means to estimate the Seebeck coefficients for the tested FM/NM pairings, providing further insight into the charge and heat flow in such nanoscopic spintronic devices. Published by the American Physical Society2024more » « lessFree, publicly-accessible full text available December 1, 2025
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Abstract Large stocks of soil carbon (C) and nitrogen (N) in northern permafrost soils are vulnerable to remobilization under climate change. However, there are large uncertainties in present‐day greenhouse gas (GHG) budgets. We compare bottom‐up (data‐driven upscaling and process‐based models) and top‐down (atmospheric inversion models) budgets of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) as well as lateral fluxes of C and N across the region over 2000–2020. Bottom‐up approaches estimate higher land‐to‐atmosphere fluxes for all GHGs. Both bottom‐up and top‐down approaches show a sink of CO2in natural ecosystems (bottom‐up: −29 (−709, 455), top‐down: −587 (−862, −312) Tg CO2‐C yr−1) and sources of CH4(bottom‐up: 38 (22, 53), top‐down: 15 (11, 18) Tg CH4‐C yr−1) and N2O (bottom‐up: 0.7 (0.1, 1.3), top‐down: 0.09 (−0.19, 0.37) Tg N2O‐N yr−1). The combined global warming potential of all three gases (GWP‐100) cannot be distinguished from neutral. Over shorter timescales (GWP‐20), the region is a net GHG source because CH4dominates the total forcing. The net CO2sink in Boreal forests and wetlands is largely offset by fires and inland water CO2emissions as well as CH4emissions from wetlands and inland waters, with a smaller contribution from N2O emissions. Priorities for future research include the representation of inland waters in process‐based models and the compilation of process‐model ensembles for CH4and N2O. Discrepancies between bottom‐up and top‐down methods call for analyses of how prior flux ensembles impact inversion budgets, more and well‐distributed in situ GHG measurements and improved resolution in upscaling techniques.more » « lessFree, publicly-accessible full text available October 1, 2025