Abstract
We study the novel interference mechanism of the long-range proximity effect in superconductor/ferromagnet/superconductor (SFS) structures in the ballistic regime. Even a small non-collinear magnetic domain near the center of a ferromagnetic weak link is shown to restore the singlet supercurrent inherent to the normal metal. The underlying physics of the effect is the magnetic scattering of the Cooper pair by the domain, which reverses total momentum of the pair in the ferromagnet and thus compensates the phase gain before and after the spin-flip scattering. The above phenomenon opens a way to easily control the properties of SFS junctions and, inversely, to manipulate the magnetic moment via the Josephson current.
Highlights
Josephson junctions with a ferromagnetic (F) metal weak link is known to reveal a very strong decrease of the critical current compared to a normal metal weak link
In order to elucidate the peculiarities of the Cooper pairs scattering with a spin-flop transition of electrons it is convenient to introduce the new functions f± = fs ± ftx which describes the pairs with zero spin projection and a reversed spin arrangement
The equations (5) can be drastically simplified if the direction of the exchange field coincides with a spin quantisation axis x:
Summary
Josephson junctions with a ferromagnetic (F) metal weak link is known to reveal a very strong decrease of the critical current compared to a normal metal weak link (see Refs. [1, 2] for review). Measurable quantities should be calculated as the superpositions of fast oscillating contributions eiγ from different trajectories and, rapidly vanish with the increasing distance L and displays a short-range (∼ ξh) behavior It should be noted though, that a simple domain structure consisting of two F layers with opposite orientations of exchange field cancels the phase gain γ and suppresses the destructive effect of an exchange field [3, 5]. Published under licence by IOP Publishing Ltd with aligned spins (with equal-spin pairs) are generated by a thin ferromagnetic domain [11, 12], located between superconducting lead and a thick central non-collinear domain Since these triplet pairs bind electrons with exactly the same de-Broglie wave length, they do not dephase, thereby leading to long-range proximity effect.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
