2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/155902We propose a dynamical explanation of the Meissner effect in superconductors and predict the existence of a spin Meissner effect: that a macroscopic spin current flows within a London penetration depth $λ_L$ of the surface of superconductors in the absence of applied external fields, with carrier density = the superfluid density and carrier speed $v=\hbar/(4m_eλ_L$) ($m_e=$bare electron mass). The two members of a Cooper pair circulate in orbits of radius $2λ_L$ in opposite direction and the spin current in a Cooper pair has orbital angular momentum $\hbar$. Our description also provides a 'geometric' interpretation of the difference between type I and type II superconductors.Interpretation of type I vs. type II behavior added (fig. 2)SuperconductivityStrongly Correlated Electronstext