Ferromagnetic Film on a Superconducting Substrate

Abstract

We study the equilibrium domain structure and magnetic flux around a ferromagnetic (FM) film with perpendicular magnetization M_0 on a superconducting (SC) substrate. At 4πM_0<H_{c1} the SC is in the Meissner state and the equilibrium domain width in the film, l, scales as (l/4πλ_{L}) = (l_{N}/4πλ_{L})^{2/3} with the domain width on a normal (non-superconducting) substrate, l_{N}/4πλ_L >> 1. Here λ_L is the London penetration length. For 4πM_0 > H_{c1} and l_{N} in excess of about 35 λ_{L}, the domains are connected by SC vortices. We argue that pinning of vortices by magnetic domains in FM/SC multilayers can provide high critical currents.

4 pages, 2 figures, submitted to PRB