Josephson Effect in Magnetic Superconductors with Spiral Magnetic Order

Abstract

It is shown that in magnetic superconductors with spiral magnetic order the Josephson current has an additional contribution which depends: (i) on the relative orientation (magnetic phase) $θ=θ_{L}-θ_{R}$ of magnetizations on the left ($L$) and right ($R$) banks of the contact, (ii) on the junction helicity $χ=χ_{L}χ_{R}$, (with spiral helicity $χ_{L(R)}=\pm 1$), i.e. $J=[J_{c}-J_χ\cos θ]\sin ϕ$ with $ϕ=ϕ_{L}-ϕ_{R}$. The ratio $R_χ\equiv J_χ/J_{c}$ is calculated as a function of the superconducting order parameter $Δ$, the exchange field energy $h$ and the wave vector $Q$ of the spiral magnetic structure. The $π$-Josephson contact can be realized in such a system in some region of parameters. Some possible consequences of this new phase relation is also analyzed.