2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/157532Here we present details of a calculation that allows us to extract a surface density of unpaired spins from flux vs. temperature experiments performed on field-cooled dc Superconducting QUantum Interference Devices (dc SQUIDs).5 pages, 5 figures; added details of device fabricationSuperconductivitytext