2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/22437By numerically solving models with competing superconducting and antiferromagnetic orders, we study the magnetic field dependence of the antiferromagnetic moment in both the weak and strong field regimes. Through a omparison with the neutron scattering results of Kang et al and Matsuura et al.on $Nd_{1.85}Ce_{0.15}CuO_4$, we conclude that this system is close to a SO(5) symmetric critical point. We also make a quantitative prediction on increasing the upper critical field $B_{c2}$ and the superconducting transition temperature $T_c$ by applying an in-plane magnetic field.4 pages, 3 figures v3: final version PRL 92, 107002 (2004)Superconductivitytext