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) $\theta ={\theta }_L-{\theta }_R$ of magnetizations on the left ($L$) and right ($R$) banks of the contact, (ii) on the junction helicity $\chi ={\chi }_L{\chi }_R$, (with spiral helicity ${\chi }_{L(R)}=\pm 1$), i.e. $J=[J_c-J_{\chi }\cos \theta ]\sin \varphi$ with $\varphi ={\varphi }_L-{\varphi }_R$. The ratio $R_{\chi }\equiv J_{\chi }/J_c$ is calculated as a function of the superconducting order parameter $\Delta$, the exchange field energy $h$ and the wave vector $Q$ of the spiral magnetic structure. The $\pi$-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.

RevTex 8 pages. Replacing with a new version with corrected error