Surface effects in magnetic superconductors with a spiral magnetic structure

Abstract

We consider a magnetic superconductor (MS) with a spiral magnetic structure. On the basis of generalized Eilenberger and Usadel equations, we show that near the boundary of the MS with an insulator (I) or vacuum, the condensate (Gor’kov’s) Green’s functions are disturbed by boundary conditions and differ essentially from their values in the bulk. Corrections to the bulk quasiclassical Green’s functions oscillate with the period of the magnetic spiral, 2π∕Q, and decay inside the superconductor over a length of the order vF∕2πT (ballistic limit) or D∕πT (diffusive limit), where Q is the wave vector of the magnetic spiral, D=vFl∕3 is the diffusion coefficient, vF is the Fermi velocity, and l is the mean free path. We calculate the dc Josephson current in a MS/I/MS tunnel junction and show that the critical Josephson current differs substantially from that obtained with the help of the tunnel Hamiltonian method and bulk Green’s functions.

Source-reported materials — not catalogue approval

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